QA: Do not pass "--bridge" to "gnt-cluster init"

Commit ec0652ad (June 2009) removed the option.

This is a cherry-pick of master commit
78453739

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

qa/qa_cluster.py

@@ -113,7 +113,6 @@ def TestClusterInit(rapi_user, rapi_secret):
 
   bridge = qa_config.get("bridge", None)
   if bridge:
-    cmd.append("--bridge=%s" % bridge)
     cmd.append("--master-netdev=%s" % bridge)
 
   cmd.append(qa_config.get("name"))