DL TS allocation: add test case to show TS allocation bug for 2nd DL TBF

This patch adds a test case test_2_consecutive_dl_tbfs which
expects a current bug with TS allocation for 2nd DL TBF.
The test's expectation is corrected along with the bug fix in a
subsequent commit

Related: OS#1792

Change-Id: I890e4fbb2b64037e051433e70082a197e2a929a6
2 files changed