Change ACTION_APP_OPEN_BY_DEFAULT_SETTINGS to standard format

This was originally introduced as an @hide API, but was exposed as part
of changes to app links. The old constant value was maintained, but it
can be migrated to the standard format and Settings can just catch
both.

Bug: 184370492

Test: manual, test app that launches using action

Change-Id: I904bd816da6c20a1dfdb207f8d4d486bb7be5cd5