TC_mme_pool_all_reject S1GW_Tests

Failing for the past 7 builds since #526

Took 10 sec (from Titan)

Stack Trace

Timeout waiting for CONN_DOWN from pool server 0
      S1GW_Tests.ttcn:1404 S1GW_Tests control part
      S1GW_Tests.ttcn:1135 TC_mme_pool_all_reject testcase