TC_mme_pool_all_reject S1GW_Tests

Failing for the past 10 builds since #526

Took 10 sec (from Titan)

Stack Trace

Timeout waiting for CONN_DOWN from pool server 0
      S1GW_Tests.ttcn:1409 S1GW_Tests control part
      S1GW_Tests.ttcn:1139 TC_mme_pool_all_reject testcase