RANAP: reject Level 3 Complete from cells with invalid LAI
Level 3 Complete messages contain a cell identity of the calling BSC/RNC.
- Verify that we do not allow RNCs with invalid PLMN (and LAC) to send Level 3 Complete requests.
- Write a ttcn3 test that sends a LU from an RNC (Iu-interface, RANAP) that has a LAI mismatching the MSC's global PLMN.
(This issue is created as a split of #2980, to clarify the confusion we created there.)