[ECM] Defer changing op mode to MODE_DEFAULT

In Android V, we changed the default mode of
OP_ACCESS_RESTRICTED_SETTINGS from MODE_ALLOWED to MODE_DEFAULT. This
means all apps will, immediately upon being installed, have this op's
mode set to MODE_DEFAULT.

But, this resulted in a bug: an app with this op set to MODE_ALLOWED
on Android pre-V will, as soon as the device upgrades to Android V,
suddenly change to MODE_DEFAULT. This is due to a pre-existing bug
with the app op system.

This change changes the default mode back to MODE_ALLOWED to avoid
this, and updates to MODE_DEFAULT upon app installation.

Bug: 349456985
Flag: android.permission.flags.enhanced_confirmation_mode_apis_enabled
Test: atest CtsPermissionUiTestCases:android.permissionui.cts.EnhancedConfirmationManagerTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8bca9a43317194eaf9cb0bc07329630c4d905aac)
Merged-In: I504449fa81219d9399fa6122952b01cbf2f94d7f
Change-Id: I504449fa81219d9399fa6122952b01cbf2f94d7f