Trivial fix of doc string
Trivial fix of doc string

Doc string of BaseComputeTest::server_check_teardown was corrected

Change-Id: I3d543d7d4d5ffbedc44ef39bf46cfdfd0389b839

cisco-openstack/tempest,openstack/tempest,openstack/tempest,sebrandon1/tempest,sebrandon1/tempest,LIS/lis-tempest,Tesora/tesora-tempest,masayukig/tempest,Juniper/tempest,zsoltdudas/lis-tempest,masayukig/tempest,cisco-openstack/tempest,zsoltdudas/lis-tempest,bigswitch/tempest,Juniper/tempest,vedujoshi/tempest,vedujoshi/tempest,Tesora/tesora-tempest,bigswitch/tempest,LIS/lis-tempest