CA-90566: Fix a loss of console connection when there are many VMs.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
CA-98393/SCTX-1190: Prevent xal exception if console/vnc-port is missing.

Which can happen if disable_pv_vnc=true is specified in other-config.
This commit fixes the problem related to CA-90566.

Signed-off-by: Jerome Maloberti <jerome.maloberti@citrix.com>
Merge pull request #1323 from zli/xenserver/obelix/HFX-453

Obelix/HFX-453