Set bind_port=0 for cross-site tests

Current cross-site tests set bind_port="7200" and port_range="30" but there is an issue in JGroups where if concurrent threads try to bind to the same port, some threads can fail forever.

Set bind_port="0" to it can use any available port.

It fixes failures in cross-site tests like this: Timed out waiting for bridge view [NYC-2, LON-1] on DistSyncNonTxStateTransferTest-NodeBU after 10 SECONDS. Current bridge view is [LON-1]