(bug)(voIP) Power off button should end the call

**Describe the bug**
My dialer supports ending the call with the power off button, tried that here but didn't quite work.
**To Reproduce**
Steps to reproduce the behavior:
1. Do an audio call someone
2. Press the power off button of your device
3. Call continues

**Expected behavior**
Call to be ended

**Smartphone (please complete the following information):**
- Device: [Pixel 3a XL]
- OS: [Android 11]

**Additional context**
- App version and store [1.0.12 - F-Droid]
- Homeserver: [matrix.org]