RFR: 8352905: Open some JComboBox bugs 1

[Alisen Chung]

Updating and opening some tests

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

Commit messages:
 - open tests

Changes: https://git.openjdk.org/jdk/pull/24495/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24495&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352905
  Stats: 430 lines in 4 files changed: 430 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24495.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24495/head:pull/24495

PR: https://git.openjdk.org/jdk/pull/24495