Fix: remove confirmed events from cache.

The previous change failed to do so, now it is fixed.

Bug: b:314195198
Change-Id: I1ad13f7bc64795dfc0e541720bf1eefe9c7d29a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5404915


Reviewed-by: Josh Hilke <jrhilke@google.com>
Commit-Queue: Leonid Baraz <lbaraz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1279969}