Rename intent to start a package's Open By Default page directly.

The intent and permission were both over-verbose. Renamed them to be
more succint.

Bug: 74763823
Test: Manually check; sending an Intent with package:// scheme works, if
originated from app of same cert.

Change-Id: I789b07d4a7c0714c021b94aced39c8e4476c8ed0