RFR: 8346051: MemoryTest fails when Shenandoah's generational mode is enabled

[William Kemper]

This test makes assertions about the number of gc manager beans and the number of memory pools. The generational mode for Shenandoah adds another memory pool.

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Commit messages:
 - Fix summary, remove debugging
 - Separate test for Shenandoah's generational mode

Changes: https://git.openjdk.org/jdk/pull/22695/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22695&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346051
  Stats: 16 lines in 1 file changed: 12 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22695.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22695/head:pull/22695

PR: https://git.openjdk.org/jdk/pull/22695