Add Video Calling: CallKit reject call not working

[LuisFX]

This issue is for a: (mark with an x)

- [ x] bug report
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Start call from one device. Reject call using the CallKit's "red x" button.

Expected/desired behavior

Expect the incoming call banner to disappear. The declineIncomingCall() function is never called.