setup: Conditional statrup state for websocket proxy

Modified to set the startup state during the cleanup
for the service ovirt-websocket-proxy only if it exists.
Unconditional code was causing an issue while cleanup
as the service details were not found and cleanup was
failing with error -

"[ ERROR ] Failed to execute stage 'Misc configuration': Command
'/sbin/chkconfig' failed to execute"

Change-Id: Icbafa3ed20b9ed9ed04a16e99cae7b4ae394db1c
Bug-Url: https://bugzilla.redhat.com/1095583
Signed-off-by: Shubhendu Tripathi <shtripat@redhat.com>