[infra] Run CheckGeneratedFiles job if any .gni file is changed

Many .gni files are generated. This generation is verified via
the CheckGeneratedFiles job, so we want that to run on the CQ
if they change to catch potential issues (e.g. manually editing).

Change-Id: Ie8146be2938e021297ed8d409674a8909cc00463
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/610636
Reviewed-by: Chris Mumford <cmumford@google.com>
Reviewed-by: Arman Uguray <armansito@google.com>
2 files changed