Component Updater: Eliminate test that deletes updater prefs.

My first thought was to run the test only in Chromium-branded builds to
avoid deleting production updater data. However, the test suite only
runs (and only makes sense to run) in Chrome-branded builds.

Although it would be possible to inject a mock prefs file, the test
doesn't actually cover anything that's sensitive to the contents of the
file (unlike the tests above).

Therefore, eliminating the test seems like the easiest solution.

Fixed: 358158949
Change-Id: I785b6dc179b9c8d52f5a927b244bd82caaedce82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5802816
Auto-Submit: Joshua Pawlicki <waffles@chromium.org>
Reviewed-by: Sorin Jianu <sorin@chromium.org>
Commit-Queue: Sorin Jianu <sorin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1344926}