pcu: Fix race condition in TC_n3101_max_t3169 and TC_n3103_max_t3169

I cannot reproduce the issue in my local system with docker, probabluy
due to different performance from jenkins builder. It triggers almost
every time in jenkins nightly TTCN3 PCU_tests though.
A similar fix was already introduced recently for TC_n3105_max_t3195
since PCU started submitting empty (idle) blocks when there's no TBF
listening on that PDCH. We need to update the test to account for that,
since our TTCN3 timers are not necessarily exactly matching the one at
the PCU side.

Change-Id: Ia5344df15c612c70a6cdd7bb6f12dc7524a23bf4
1 file changed