Fix ECBM during test mode

An upstream removed duplicate ECBM exit indications from being
generated during ECBM exit. This broke the test procedure using
ril.test.emergencynumber because the modem never sends an exit
inidication in this case.

Bug: 155926465
Fixes: 158014357
Test: manual; trigger test emergency call + ECBM
Merged-In: Ia78a839c5b4a66b605ae25041fd74738ff2ab06b
Change-Id: Ia78a839c5b4a66b605ae25041fd74738ff2ab06b