Put 10% of ART run-tests in `TEST_MAPPING` group `mainline-presubmit`.

Include more ART run-tests into the `mainline-presubmit` test
group. This progressive rollout is to make sure introducing ART
run-tests to this test group won't disturb/break Android
presubmits.

Output of `art/test/utils/regen-test-files`:

  $ art/test/utils/regen-test-files
  Generated Blueprint files for 621 ART run-tests out of 919 (67%).
  Generated TEST_MAPPING entries for 379 ART run-tests out of 919 (41%):
    37 tests (10%) in `mainline-presubmit` test group.
    189 tests (50%) in `presubmit` test group.
    190 tests (50%) in `postsubmit` test group.

Test: atest --test-mapping art:mainline-presubmit
Bug: 178703264
Bug: 152374989
Change-Id: I9dff31c5044583856d1586a437fdf35dd437a8df
2 files changed