Put 5% 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 918 (67%).
  Generated TEST_MAPPING entries for 256 ART run-tests out of 918 (27%):
    12 tests (5%) in `mainline-presubmit` test group.
    128 tests (50%) in `presubmit` test group.
    128 tests (50%) in `postsubmit` test group.

Also make some stylistic changes (e.g. use list comprehensions instead
of `map()` and `lambda`; use parentheses for implied line continuation
instead of escaping line breaks with backslashes).

Test: atest --test-mapping art:mainline-presubmit
Bug: 178703264
Bug: 152374989
Change-Id: I25950b02fbd3a1cbd4193a5f7b87f8b3867bd16b
2 files changed