Stop using temp-allowlist reason to identify push msgs.

We made a temporary change a while back to identify push
messages using temp-allowlist reason so that we can get the
broadcast response stats data without needing for changes
on the client side but this logic is not needed anymore.

Bug: 217251579
Test: atest tests/tests/app.usage/src/android/app/usage/cts/UsageStatsTest.java
Change-Id: I72a09fc6bc9a7d1cd0aeced3da09a506ea4aef76