Use COMMON_OWNERS for tools/

R=machenbach@chromium.org

Change-Id: I1e85df85e8eb588a0ae97320eba6e72163d9ff18
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1684175Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62484}

tools/OWNERS

-file://INFRA_OWNERS
+file://COMMON_OWNERS
 
-per-file *DEPS=file://COMMON_OWNERS
-per-file gen-postmortem-metadata.py=file://COMMON_OWNERS
-per-file v8heapconst.py=file://COMMON_OWNERS
-per-file whitespace.txt=file://COMMON_OWNERS