Ensure enough tests on cqtast sub trybots.

This ensures chromeos-betty-chrome-gtest-and-cqtast has combined set of
cq-medium, and all public runnable mainline tests.

The guarantees no tests are reduced when migrating from amd64-generic to
betty.

The list of additional tests will be fine tuned in the future.

Bug: 497623415
Change-Id: Ia363794380796b5f1f1ac96fce90dcc019bd3ee0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7672979
Commit-Queue: Qijiang Fan <fqj@chromium.org>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Auto-Submit: Qijiang Fan <fqj@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1606887}
NOKEYCHECK=True
GitOrigin-RevId: c288aad605d6930ee97324be9264605741c469d0