chrome_cleaner/os unit tests, part 2: g-r

Remove unused chrome_cleaner::RegistryOverrideManager. All tests now use
registry_util::RegistryOverrideManager.

R=csharp

Bug: 830892
Change-Id: Ife5ed1075176436e470bac0aeb02ac271409aea5
Reviewed-on: https://chromium-review.googlesource.com/1150681
Reviewed-by: Chris Sharp <csharp@chromium.org>
Commit-Queue: Joe Mason <joenotcharles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578738}
10 files changed