BSC_Tests: Fix test case TC_err_84_unknown

The test cases used UPLINK RELEASE message as test for an unspported
message. This message is supported and does not trigger the expected RR
STATUS message. The fix uses the unsupported DTM ASSIGNMENT FAILURE
message.

To have the DTM ASSIGNMENT FAILE, it is added to
library/L3_Templates.ttcn.

Change-Id: I35877574cf4459332229e3b941918bc0a23b939f
2 files changed