ML scan: relaunched on resume

Description

When a long ML scan is done, if the scan is not finished and in the "parsing" phase, leaving the MainActivity and reopening re-launches the scan. The discover is then done again.

Expected behavior

The scan is not re-lanched.

Steps to reproduce

1. Start an initial scan with a lot of medias
2. Wait for the "parsing" phase (The app shows Parsing medias xx% xxxx/xxxxx)
3. Leave the app with HOME or BACK
4. Reopen the app -> the scan switches to Discovering xxx.

Screenshot / video

Context

App version

3.4.x branch

Android version

Android 12

Device model

Pixel 3a

App mode

Smartphone