[reader mode] Show the IPH when the action is suppressed

This is due to the RM IPH being suppressed by the CPA IPH. This work
around will ensure that the RM IPH has more than one opportunity to be
shown thus increasing the likelihood that it will be shown.
* Changes to how the ReaderModeActionRateLimiter.Observer works.
* Event flow is now coming directly from the notifyActionShown method.

Bug: 441586248
Change-Id: I02efed41f1fa92a5185799a927702f095a800d84
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6909618
Commit-Queue: Brandon Wylie <wylieb@google.com>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1510415}