RFR: 8335932: GenShen: Fix old heuristic unit test [v2]

[William Kemper]

> This isn't really a unit test and it must be run with Shenandoah enabled, but it exercises a hard to reach code path. The test has suffered some bit-rot* of late that needs to be addressed.
> 
> * We no longer set soft-max-capacity on the old generation.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Skip destructor actions when disabled

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Changes:
  - all: https://git.openjdk.org/shenandoah/pull/458/files
  - new: https://git.openjdk.org/shenandoah/pull/458/files/4e7e2b38..cf114eb5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=458&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=458&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/458.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/458/head:pull/458

PR: https://git.openjdk.org/shenandoah/pull/458