Process rcsVolteSingleRegistration if it is not provided or roaming

Bug: 186884505
Test: atest TeleServiceTests:com.android.phone.RcsProvisioningMonitorTest
Test: atest FrameworksTelephonyTests:com.telephony.ims.RcsConfigTest
Merged-In: I800ba7cfda4fdd9bd2590a12c23c33ee72b07396
Change-Id: I132f40b334c9a2d33b3517b4897c52b0554c994d