Remove Linux CHECK and TODO from uninstall pinging

Revert the changes of crrev.com/c/4409640. Remove CHECK statements added
as a temporary debugging measure.

Bug: 1431487
Change-Id: Icdb963be9ddda98715f69cb279ade35b6aea59f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4550364


Reviewed-by: Sorin Jianu <sorin@chromium.org>
Commit-Queue: Sorin Jianu <sorin@chromium.org>
Auto-Submit: Noah Rose Ledesma <noahrose@google.com>
Cr-Commit-Position: refs/heads/main@{#1147411}