RFR: 8283183: Skip failing PredefinedMeshManagerTest tests

[Kevin Rushforth]

We continue to get intermittent test failures in `PredefinedMeshManagerTest` due to an OOM error. See the GitHub Actions run for [PR 753](https://github.com/openjdk/jfx/pull/753/checks?check_run_id=5559141397) for a recent failure. This test failure is tracked by [JDK-8282449](https://bugs.openjdk.java.net/browse/JDK-8282449). Until that test bug is fixed, I propose to skip the two test methods, `cylinderCacheTest` and `sphereCacheTest`, that allocate large meshes and are prone to OOM errors.

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Commit messages:
 - 8283183: Skip failing PredefinedMeshManagerTest tests

Changes: https://git.openjdk.java.net/jfx/pull/754/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=754&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283183
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/754.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/754/head:pull/754

PR: https://git.openjdk.java.net/jfx/pull/754