Proximity sensor stays active after voice call is ended

### Steps to reproduce

1. Make a voice call via Element
2. Finish the call
3. Close Element and go to main menu or open any other app, so Element continues running in background
4. Cover proximity sensor by your finger

### Outcome

#### What did you expect?
Element should only watch proximity sensor & turn off the screen during the call

#### What happened instead?
Element continuosly watches proximity sensor & turns off the screen even after the call is finished long time ago & Element running in the background & you are holding phone in your hands and not near your head

The workaround is pressing "Force stop" button for Element in Android apps menu. After that display doesn't turn off anymore if you accidentally cover proximity sensor with your finger while using your phone.

### Your phone model

Samsung Galaxy A5 (2017)

### Operating system version

Android 8.0

### Application version and app store

Element 1.4.25, F-Droid

### Homeserver

matrix.org

### Will you send logs?

No

### Are you willing to provide a PR?

No