Hang up EmergencyDial after Trigger in VTS

The whole test case run emergencyDial.RadioHidlTest_v1_4 first and then
 come after startNetworkScan.RadioHidlTest_v1_4 test case immediately
 (within ~3 secs) the NWscan failure is device in emergency call in
 progress/connected while doing emergencyDial.RadioHidlTest_v1_4 test

Although emergencyDial.RadioHidlTest_v1_4 only care about command/response
 is successful or not and don't care call is established or not, modem do
 care about call condition is in idle/progress/connected state before it
 can do NWscan

When there's dedicated channel established, modem can not perform AP
 request NWscan in parallel as we are single HW modem restriction.

Test: run vts
Bug: 135595082
Change-Id: Iecba54b93b96d33b57bc59e00f082ff133d2e57b