Remove no_wait ovs flag from vmw_nsx 3rd party lib

The no_wait flag can trigger a race conditon with ip addr flush
if the public bridge is not yet up. Due to this race condition
the local route for the external subnet might not be added.

The patch also renames br-ex to $PUBLIC_BRIDGE in some places

Change-Id: I11335c99dba580e7ca26b0b15b0df8dead367fdc
Merge "Remove no_wait ovs flag from vmw_nsx 3rd party lib"