msc: add first a5/4 tests

All msc tests involving classmarks suffer from the same problem: if a
existing subscriber is reused the old classmarks will stick, since the
msc only overwrites updated parts of the cm when receiving a new cm, so
"downgrading" the existing classmark information is not possible.

This is circumvented here here by using different imsi suffixes,
the last param passed to f_start_handler.

Additionally the handler will now properly respond to cm requests
by the msc, i.e. in case the early cm is not sufficient for a5/4
because it lacks cm3, so the msc attempts once to query the cm,
hoping to get a cm3.

Related: SYS#5324
Change-Id: Idc055a006b325f58a5eafa88bc4415181b3500a2
6 files changed