[bug] database randomly gets locked all the time

### Checks

- [x] I have read the Wiki, searched the open issues, and still think this is a new bug.

### Explain the problem clearly and succinctly:

something changed in one of the latest versions of KeePassDX.

on my phone, the database randomly gets locked all the time when switching to other apps.

I think I've spotted what's causing this issue for me.

before, KeePassDX would minimize itself after unlocking the database.

but now, KeePassDX **closes** itself after unlocking the database, leaving only the notification behind.

this new behaviour causes the database to randomly get locked on phones with limited RAM.

### Describe what you expected to happen:

the database shouldn't get locked randomly.

this was not happening before.

### KeePassDX version:

4.2.3

### Build:

Free

### Database version:

_No response_

### File provider (`content://` URI)

_No response_

### Android version:

Android 9

### Android device:

Samsung Galacy A10

### Additional context:

_No response._

Start by reproducing the behavior described on Android 9 with KeePassDX 4.2.3, especially after unlocking and switching to another app. Compare the app's closing behavior with the expected minimization behavior; done means the database does not lock unexpectedly during app switching under the reported conditions.

Written by the indexing model from the issue text.