Ensure turning off photo picker flag doesn't allow permission expansion

This change ensures that READ_MEDIA_VISUAL_USER_SELECTED is
considered a "partial grant", no matter if the feature is enabled or
disabled

Bug: 288144265
Fixes: 294596364
Relnote: prevent permission expansion if a device config flag is flipped
Test: manual
Change-Id: I1a419b95743bd43b084a4e28c8e82e579d67a0fd