(fix gate) Don't source openrc in gate run
(fix gate) Don't source openrc in gate run

The latest set of changes to devstack include one
where enabling a plugin more than once now causes
a fatal error.  Trovestack code sources openrc,
which sources other files that eventually call
enable_plugin on the trove module.  Unfortunately
since trovestack also sources some of the same
files, this causes the error to be triggered.

The fix is to remove the call to openrc and just
set the credentials manually.

Change-Id: Iec71474ccfe757c8384c0b4e4b0758636668aebe

hplustree/trove,openstack/trove,openstack/trove,zhangg/trove,zhangg/trove,hplustree/trove