fix SCCPlite BSC tests: send IPA ID ACK, not GET

From libosmo-sccp.git Icffda98579e676ab6ca63c9c22cf5d151c4fe95f on, we expect
an IPA ID ACK upon first connecting, not an IPA ID GET. This might be specific
to the one MSC tested so far, but it's the status quo.

Make the IPA server in IPA_Emulation configurable, to conform and send the IPA
ID ACK upon connecting.  This fixes the ttcn3-bsc-tests,SCCPlite suite, broken
by above libosmo-sccp commit.

For other IPA clients, it is so far required to send the IPA ID GET, so only
configure the SCCPlite server in BSSAP_Adapter.ttcn to send IPA ID ACK, and
leave the others unchanged.

Related: OS#3500 OS#3498
Related: Icffda98579e676ab6ca63c9c22cf5d151c4fe95f (libosmo-sccp)
Change-Id: I34b6296a1a408729802a9659c6524c0f67a2f4fe
2 files changed