Remove XenAPI use of eventlet tpool
Remove XenAPI use of eventlet tpool

XenAPI implementation does not block, even with it using SSL, therefore
there's no need to use eventlet's tpool.

Change-Id: I33ef4140068c8af06d27a075f52379581790c647

savi-dev/nova,usc-isi/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,NewpTone/stacklab-nova,shahar-stratoscale/nova,maoy/zknova,watonyweng/nova,leilihh/nova,devendermishrajio/nova_test_latest,DirectXMan12/nova-hacking,ewindisch/nova,shahar-stratoscale/nova,tangfeixiong/nova,bclau/nova,iuliat/nova,sridevikoushik31/openstack,zhimin711/nova,alexandrucoman/vbox-nova-driver,zaina/nova,bgxavier/nova,sacharya/nova,maoy/zknova,Juniper/nova,vladikr/nova_drafts,Triv90/Nova,openstack/nova,yrobla/nova,sebrandon1/nova,mikalstill/nova,eonpatapon/nova,ted-gould/nova,fnordahl/nova,berrange/nova,projectcalico/calico-nova,zaina/nova,silenceli/nova,cloudbase/nova,sridevikoushik31/nova,CiscoSystems/nova,josephsuh/extra-specs,dims/nova,tianweizhang/nova,rrader/nova-docker-plugin,paulmathews/nova,eayunstack/nova,ewindisch/nova,usc-isi/extra-specs,klmitch/nova,devendermishrajio/nova,openstack/nova,tealover/nova,barnsnake351/nova,yrobla/nova,jeffrey4l/nova,joker946/nova,Triv90/Nova,hanlind/nova,alvarolopez/nova,luogangyi/bcec-nova,NewpTone/stacklab-nova,NewpTone/stacklab-nova,Yuriy-Leonov/nova,mahak/nova,aristanetworks/arista-ovs-nova,maheshp/novatest,TwinkleChawla/nova,j-carpentier/nova,projectcalico/calico-nova,akash1808/nova_test_latest,CloudServer/nova,citrix-openstack-build/nova,varunarya10/nova_test_latest,qwefi/nova,shail2810/nova,JioCloud/nova_test_latest,usc-isi/extra-specs,redhat-openstack/nova,SUSE-Cloud/nova,rahulunair/nova,badock/nova,zzicewind/nova,OpenAcademy-OpenStack/nova-scheduler,rajalokan/nova,houshengbo/nova_vmware_compute_driver,eharney/nova,vmturbo/nova,eayunstack/nova,takeshineshiro/nova,tianweizhang/nova,BeyondTheClouds/nova,angdraug/nova,blueboxgroup/nova,DirectXMan12/nova-hacking,jianghuaw/nova,aristanetworks/arista-ovs-nova,rahulunair/nova,blueboxgroup/nova,dawnpower/nova,zzicewind/nova,fajoy/nova,thomasem/nova,gspilio/nova,plumgrid/plumgrid-nova,tangfeixiong/nova,dstroppa/openstack-smartos-nova-grizzly,JianyuWang/nova,sridevikoushik31/nova,spring-week-topos/nova-week,NoBodyCam/TftpPxeBootBareMetal,maelnor/nova,hanlind/nova,JianyuWang/nova,thomasem/nova,tanglei528/nova,DirectXMan12/nova-hacking,scripnichenko/nova,affo/nova,Juniper/nova,bigswitch/nova,akash1808/nova,nikesh-mahalka/nova,savi-dev/nova,Tehsmash/nova,maheshp/novatest,noironetworks/nova,noironetworks/nova,leilihh/novaha,sridevikoushik31/openstack,ruslanloman/nova,isyippee/nova,Triv90/Nova,cloudbase/nova-virtualbox,JioCloud/nova,bigswitch/nova,cernops/nova,sridevikoushik31/openstack,klmitch/nova,cyx1231st/nova,imsplitbit/nova,rajalokan/nova,leilihh/novaha,Juniper/nova,fajoy/nova,mikalstill/nova,Stavitsky/nova,Francis-Liu/animated-broccoli,hanlind/nova,virtualopensystems/nova,dstroppa/openstack-smartos-nova-grizzly,gooddata/openstack-nova,phenoxim/nova,leilihh/nova,affo/nova,cloudbau/nova,alexandrucoman/vbox-nova-driver,BeyondTheClouds/nova,yatinkumbhare/openstack-nova,MountainWei/nova,aristanetworks/arista-ovs-nova,isyippee/nova,gspilio/nova,Tehsmash/nova,angdraug/nova,TwinkleChawla/nova,SUSE-Cloud/nova,ntt-sic/nova,sebrandon1/nova,cloudbau/nova,Francis-Liu/animated-broccoli,nikesh-mahalka/nova,fnordahl/nova,devendermishrajio/nova,yrobla/nova,gooddata/openstack-nova,NoBodyCam/TftpPxeBootBareMetal,dstroppa/openstack-smartos-nova-grizzly,openstack/nova,vmturbo/nova,cloudbase/nova,belmiromoreira/nova,usc-isi/extra-specs,saleemjaveds/https-github.com-openstack-nova,mahak/nova,cernops/nova,qwefi/nova,zhimin711/nova,cernops/nova,Yusuke1987/openstack_template,j-carpentier/nova,kimjaejoong/nova,tanglei528/nova,whitepages/nova,raildo/nova,vmturbo/nova,cloudbase/nova,BeyondTheClouds/nova,akash1808/nova,berrange/nova,akash1808/nova_test_latest,silenceli/nova,mikalstill/nova,tudorvio/nova,CloudServer/nova,petrutlucian94/nova_dev,NeCTAR-RC/nova,devoid/nova,adelina-t/nova,citrix-openstack-build/nova,CCI-MOC/nova,watonyweng/nova,joker946/nova,vladikr/nova_drafts,shootstar/novatest,jeffrey4l/nova,usc-isi/nova,gspilio/nova,alvarolopez/nova,shootstar/novatest,sridevikoushik31/nova,yosshy/nova,felixma/nova,alaski/nova,alaski/nova,maoy/zknova,apporc/nova,bgxavier/nova,scripnichenko/nova,eharney/nova,petrutlucian94/nova,adelina-t/nova,savi-dev/nova,double12gzh/nova,houshengbo/nova_vmware_compute_driver,rickerc/nova_audit,cyx1231st/nova,TieWei/nova,maheshp/novatest,paulmathews/nova,sacharya/nova,ted-gould/nova,CEG-FYP-OpenStack/scheduler,luogangyi/bcec-nova,takeshineshiro/nova,plumgrid/plumgrid-nova,varunarya10/nova_test_latest,petrutlucian94/nova,JioCloud/nova,Brocade-OpenSource/OpenStack-DNRM-Nova,tudorvio/nova,usc-isi/nova,vmturbo/nova,mandeepdhami/nova,saleemjaveds/https-github.com-openstack-nova,Metaswitch/calico-nova,mahak/nova,viggates/nova,yosshy/nova,mmnelemane/nova,mgagne/nova,devoid/nova,imsplitbit/nova,CCI-MOC/nova,barnsnake351/nova,phenoxim/nova,CEG-FYP-OpenStack/scheduler,apporc/nova,jianghuaw/nova,sebrandon1/nova,jianghuaw/nova,viggates/nova,Stavitsky/nova,rickerc/nova_audit,yatinkumbhare/openstack-nova,devendermishrajio/nova_test_latest,LoHChina/nova,ntt-sic/nova,tealover/nova,virtualopensystems/nova,MountainWei/nova,rajalokan/nova,spring-week-topos/nova-week,felixma/nova,Juniper/nova,Yuriy-Leonov/nova,maelnor/nova,JioCloud/nova_test_latest,klmitch/nova,whitepages/nova,gooddata/openstack-nova,mgagne/nova,klmitch/nova,TieWei/nova,orbitfp7/nova,double12gzh/nova,Yusuke1987/openstack_template,belmiromoreira/nova,edulramirez/nova,iuliat/nova,LoHChina/nova,petrutlucian94/nova_dev,dawnpower/nova,dims/nova,paulmathews/nova,jianghuaw/nova,raildo/nova,Metaswitch/calico-nova,CiscoSystems/nova,mandeepdhami/nova,shail2810/nova,josephsuh/extra-specs,ruslanloman/nova,NeCTAR-RC/nova,kimjaejoong/nova,josephsuh/extra-specs,gooddata/openstack-nova,orbitfp7/nova,fajoy/nova,mmnelemane/nova,sridevikoushik31/nova,bclau/nova,redhat-openstack/nova,cloudbase/nova-virtualbox,NoBodyCam/TftpPxeBootBareMetal,houshengbo/nova_vmware_compute_driver,rrader/nova-docker-plugin,edulramirez/nova,rajalokan/nova,badock/nova,eonpatapon/nova,OpenAcademy-OpenStack/nova-scheduler,rahulunair/nova