Revert "Reduce number of tests run in art-gcstress-gcverify."

This reverts commit 4f64fbb7.

Reason for revert: The initial issue (timeout on build bots) should
have been addressed by https://android-review.googlesource.com/635812.

Bug: 74196452
Bug: 74225325
Change-Id: Ibbbd3f8747f57d0e00bc4bc960eb5b4dc1fa22e0
Test: Start ./test/testrunner/run_build_test_target.py -j30 art-gcstress-gcverif