[Notif] Disable "Customize" for blocking helper

Rolling forward ag/3824685.

Update UI to hide customize when blocking helper is showing. Fixed a
small problem with context.getString too where it was unnecessarily
passing in a format string argument.

Change-Id: I07feba206051f6804d2a537c468fcde8d85f0940
Test: Visually
Test: Ran atest NotifInfoTest with new test case (rebased this time)
Fixes: 77321231