[presubmit] Do not pass dirmd path to CheckDirMetadataFormat

ChecksCommon runs third_party/depot_tools/dirmd which pollutes the
depot_tools directory. Don't pass a dirmd path and let
CheckDirMetadataFormat choose one outside third_party.

Bug: 416037494
Change-Id: Ida1c0d23d82b0a72653838acf2b779b297f5d0e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6518927
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Auto-Submit: Gavin Mak <gavinmak@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1457938}