Convert try/expect/else as per new Tempest style.
Convert try/expect/else as per new Tempest style.

Test modified: test_get_metadata_of_alt_account_server_fails

Modifications:
As per new Tempest style guidelines, convert "try/expect/else"
statements into "assertRaises".

In order to ensure that other tests remain unaffected
because of this change, replace "finally" with "addCleanup".

Partially implements Blueprint update-expected-exception-tests.

Change-Id: I0b8be10c90111c5faa78a8955e0370fa558e7bfd

adkerr/tempest,citrix-openstack-build/tempest,BeenzSyed/tempest,yamt/tempest,masayukig/tempest,openstack/tempest,izadorozhna/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,hayderimran7/tempest,queria/my-tempest,manasi24/jiocloud-tempest-qatempest,BeenzSyed/tempest,tudorvio/tempest,neerja28/Tempest,ebagdasa/tempest,vedujoshi/os_tempest,pandeyop/tempest,roopali8/tempest,danielmellado/tempest,redhat-cip/tempest,vedujoshi/os_tempest,ntymtsiv/tempest,Juraci/tempest,zsoltdudas/lis-tempest,Juraci/tempest,NexusIS/tempest,itskewpie/tempest,nunogt/tempest,bigswitch/tempest,izadorozhna/tempest,jaspreetw/tempest,roopali8/tempest,rzarzynski/tempest,Mirantis/tempest,LIS/lis-tempest,tonyli71/tempest,Mirantis/tempest,hayderimran7/tempest,adkerr/tempest,bigswitch/tempest,Lilywei123/tempest,vedujoshi/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,Tesora/tesora-tempest,yamt/tempest,rakeshmi/tempest,manasi24/tempest,CiscoSystems/tempest,alinbalutoiu/tempest,cloudbase/lis-tempest,pczerkas/tempest,manasi24/jiocloud-tempest-qatempest,openstack/tempest,CiscoSystems/tempest,eggmaster/tempest,pandeyop/tempest,flyingfish007/tempest,sebrandon1/tempest,hpcloud-mon/tempest,Vaidyanath/tempest,itskewpie/tempest,nunogt/tempest,citrix-openstack-build/tempest,xbezdick/tempest,citrix-openstack/build-tempest,tonyli71/tempest,cisco-openstack/tempest,dkalashnik/tempest,Juniper/tempest,tudorvio/tempest,afaheem88/tempest_neutron,jamielennox/tempest,Lilywei123/tempest,ebagdasa/tempest,vmahuli/tempest,redhat-cip/tempest,xbezdick/tempest,jamielennox/tempest,alinbalutoiu/tempest,cloudbase/lis-tempest,ntymtsiv/tempest,danielmellado/tempest,akash1808/tempest,armando-migliaccio/tempest,akash1808/tempest,queria/my-tempest,NexusIS/tempest,rakeshmi/tempest,pczerkas/tempest,afaheem88/tempest,hpcloud-mon/tempest,manasi24/tempest,dkalashnik/tempest,Juniper/tempest,masayukig/tempest,cisco-openstack/tempest,Vaidyanath/tempest,jaspreetw/tempest,afaheem88/tempest_neutron,rzarzynski/tempest,vmahuli/tempest,afaheem88/tempest,flyingfish007/tempest,LIS/lis-tempest,varunarya10/tempest,citrix-openstack/build-tempest,armando-migliaccio/tempest,vedujoshi/tempest,sebrandon1/tempest,zsoltdudas/lis-tempest,eggmaster/tempest,Tesora/tesora-tempest,JioCloud/tempest,JioCloud/tempest,varunarya10/tempest,neerja28/Tempest