Clean up db.sqla.api.instance_* methods
Clean up db.sqla.api.instance_* methods

Remove session parameter from public db methods:
instance_get_all_by_filters
instance_metadata_get
instance_metadata_update
instance_system_metadata_get
instance_system_metadata_update

They were never called with session parameter and they
are fully covered by tests so we are able just to remove
session parameter.

Clean up instance_metadata_get and instance_system_metadata_get
Convert rows to dict in one line instead of 4.

blueprint db-session-cleanup

Change-Id: Ib2f50cc4b5a7a2e283d891141a88c7b1ff9f7d43

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