msc: add TC_cmserv_tmsi_unknown()

We already have TC_cmserv_imsi_unknown, but lack a test that shows CM Service
Request behavior for an unknown TMSI.

Looking at OS#4721 I vaguely expected an ID Request to also happen during CM
Service Request, but instead we reject the unknown TMSI completely, and require
the MS to perform a proper LU subsequently.

Related: OS#4721
Change-Id: I54e5efcf4c31625205c99338379a2055633acde9
1 file changed