Add buganizer ID to DIR_METADATA

This helps predator correctly assigning components.

Bug: chromium:341800538
Change-Id: Ibe8117563f6a48b0e2f194351ea0cc59b1baaa06
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/921476
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
Auto-Submit: Paul Semel <paulsemel@chromium.org>
Commit-Queue: Kaylee Lubick <kjlubick@google.com>