Update chrome_cleaner_internal path to //chrome/chrome_cleaner/internal

* Add a chrome_cleaner_internal_root var that can be overridden on builders
  that still use the internal path.
* Add //chrome/chrome_cleaner/internal to .gitignore

A followup will add //chrome/chrome_cleaner/internal to the src-internal DEPS.

R=​proberge

(cherry picked from commit 0ebe2d5dcfab6b8ec596712a776776e78bb08d38)

Bug: 985787
Change-Id: I25064555dba516aec739ccfa0c768766730e6709
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1745399
Reviewed-by: proberge <[email protected]>
Commit-Queue: Joe Mason <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#685704}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1752072
Reviewed-by: Joe Mason <[email protected]>
Cr-Commit-Position: refs/branch-heads/3865@{#355}
Cr-Branched-From: 0cdcc6158160790658d1f033d3db873603250124-refs/heads/master@{#681094}
6 files changed