Update osmo-msc to use osmo-mgw
Patches to migrate osmo-msc to use osmo-mgw instead of osmo-bsc_mgcp are going to be merged soon. Actually, the osmo-mgw parts are already merged which affect osmo-bsc and osmo-msc. Until patches for those are merged and we move to osmo-mgw, voice tests are goign to be failing.
We can test osmo-msc<->osmo-mgw once the following patches are merged and trials are available:
For bsc it is this one: https://gerrit.osmocom.org/#/c/4964/
for MSC it is this one: https://gerrit.osmocom.org/#/c/4980/