bug(android): 'Cloud Download KeyboardLexicalModels' is running on the background after installing a Keyboard or Invoking Keyman

**Describe the bug**
I noticed that there is a message 'Cloud Download KeyboardLexicalModels' appears and running in the background of the Keyman app whenever I try to install a new keyboard (with dictionary)

**To Reproduce**
1. Install Keyman 15.0.270 stable release.
2. Open Keyman In-App
3. Click Settings / Installed languages.
4. Verify that the Installed languages menu appears.
5. Click the Plus button which appears at the bottom of the menu.
6. Enter 'Khmer Angkor' from the Search text box.
7. Verify that the Khmer Angkor Keyboard appears under the Results.
8. Install Khmer Angkor Keyboard.
9. Here, I noticed that there is a download manager which running behind the Keyman App for some time with the message 'Cloud Download KeyboardLexicalModels..downloading..'.
10. Install sil_cameroon_qwerty Keyboard.
11. Again the download manager is running on the background of keyman.

**Expected behavior**
It would be better if it is not appear on the background of keyman whenever we added a new keyboard.

**Screenshots**
..in Android 8.0 / API 26 emulator

..Android 11 / Mobile device

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**Keyman for Android:**
- Device: API 26 Android emulator, Redmi Note 8 Pro Mobile
- OS: Android 8, Android 11
- Keyman version: 15.0.270
- Target Application: Keyman InApp

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**Keyboard**
- Keyboard name: Khmer Angkor
- Keyboard version: 1.3
- Language name: Khmer

**Additional context**
I noticed that this message (ie., Cloud Download KeyboardLexicalModels..)appears in my mobile when I opened keyman for the first time in a day.