RFR: Remove passing tests from ProblemList.txt

[William Kemper]

Recent test runs suggest that all but three tests are now passing. The remaining failures are believed to be fixed by https://github.com/openjdk/shenandoah/pull/248.

-------------

Commit messages:
 - Merge branch 'shenandoah-master' into some-tests-enabled
 - Disable still failing tests
 - Enable all tests so we can see where we stand

Changes: https://git.openjdk.org/shenandoah/pull/273/files
 Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=273&range=00
  Stats: 9 lines in 2 files changed: 0 ins; 6 del; 3 mod
  Patch: https://git.openjdk.org/shenandoah/pull/273.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/273/head:pull/273

PR: https://git.openjdk.org/shenandoah/pull/273