Enable all aspect ratio options in UserAspectRatioManagerTest

testGetUserMinAspectRatioEntry fails for foldables and tablets due to
some aspect ratio options being disabled. Mock Resources to return all
default aspect ratio options and strings to make test device agnostic.

Clean up unused variables and remove getLauncherApps in
UserAspectRatioManager.

Add more tests in UserAspectRatioManagerTest.

Fix: 304685321
Test: atest SettingsUnitTests:UserAspectRatioManagerTest
Change-Id: I6f4bbd60863be0c66139955507157619a5fc6662