vswitchperf: Use POD12 for VERIFY and MERGE jobs

vswitchperf: Use POD12 for VERIFY and MERGE jobs

In the past, vswitchperf's VERIFY & MERGE jobs were
executed at ericsson-build3 & build4 machines. However
VPP sometimes refuses to start properly and it is hard
to debug root cause without access to these servers.
Thus description of VERIFY & MERGE jobs was changed
to run them by default at POD12, which is dedicated
to vswitchperf project. In case that daily job is active,
then VERIFY & MERGE jobs will be executed at ericsson-build4
as before.
Execution of "make sanity" was removed, because this
target is a "stub" in vsperf makefile.

Change-Id: Iec0f788ab28425d0999811ceb5236e097cee2ff4
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>
Reviewed-by: Trevor Bramwell <tbramwell@linuxfoundation.org>