Remove experimental per app feature flag

[nbradbury]

This PR removes the experimental feature flag for per app language prefs, which enables per app prefs for all users. This targets the feature/per-app-language-prefs feature branch rather than trunk because there's much more work to do before this feature can be released (most notably, dropping the LocaleAwareActivity). In addition, we also want the experimental feature flag to be available in at least one release before removing it.

Test 1:

• Run the app on a device using Android 13 or later
• Go to App Settings and tap "Interface language"
• Note that the system dialog for "App Language" appears instead of our own
• Verify changing languages works

Test 2:

• Perform the above with an older device and verify our own language dialog appears and changing languages works

[dangermattic]

	1 Warning
⚠️	strings.xml files should only be updated on release branches, when the translations are downloaded by our automation.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21521-c62e604
	Commit	c62e604
	Direct Download	wordpress-prototype-build-pr21521-c62e604.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21521-c62e604
	Commit	c62e604
	Direct Download	jetpack-prototype-build-pr21521-c62e604.apk

Note: Google Login is not supported on these builds.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.44%. Comparing base (f537145) to head (c62e604).
Report is 11 commits behind head on feature/per-app-language-prefs.

Additional details and impacted files

@@                       Coverage Diff                       @@
##           feature/per-app-language-prefs   #21521   +/-   ##
===============================================================
  Coverage                           39.44%   39.44%           
===============================================================
  Files                                2119     2119           
  Lines                               99556    99556           
  Branches                            15313    15313           
===============================================================
  Hits                                39269    39269           
  Misses                              56806    56806           
  Partials                             3481     3481           

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[ParaskP7]

👋 @nbradbury !

I have reviewed and tested this PR as per the instructions, everything works as expected, great clean-up! 🧹 🧹 🧹

---

I have left few questions (❓)and some minor (🔍) comments for you to consider. I am going to approve this PR anyway, since none is blocking and I don't want to block progress on this. I am NOT going to merge this PR yet to give you some time to apply any of my suggestions. However, feel free to ignore them and merge the PR yourself.

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud