For DSDA devices, do not disconnect existing call

- For DSDA-enabled devices, we will not disconnect existing call on
the 1st sub when receiving (or placing) a new call on the 2nd sub.

Bug:249857869
Test: Live test on P10. New UTs:
TelephonyConnectionServiceTest#testSecondCallDifferentSubWontDisconnectForDsdaDevice()
TelephonyConnectionServiceTest#testDontDisconnectDifferentSubForDsdaDevice()

Change-Id: Ieef4516423293135459b0d3f483cb15d041d7170
2 files changed