Flag FRRO changes for Launcher preview color fix (2/3)

Flag changes in the topic:
https://googleplex-android-review.git.corp.google.com/q/topic:%22revert-30159224-revert-29910507-launcher-color-preview-fix-XVTAANIJBS-AWXALNHUNX%22

Even though this is a bug fix, the change needs to be behind a flag
because it involves CTS test changes. CTS test changes can only be
released along with API releases. Instead of a revert, which causes
merge conflicts, fix forward by flagging the changes.

Flag: android.content.res.self_targeting_android_resource_frro
Bug: 381170131
Test: atest OverlayManagerImplTest
Test: atest OverlayManagerTransactionTest
Test: atest ResourcesProviderTest
Test: manually verified with flags on and off
Change-Id: I89c0a3bd8089372925b652285093c32fd5fbec3b