RFR: 8342278: GenShen: Move non-generational mode test out of generational test configuration

[William Kemper]

Test has unintentionally configured a non-generational mode test to run under the generational test section.

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Commit messages:
 - Put non-generational mode test config under a separate test id

Changes: https://git.openjdk.org/shenandoah/pull/515/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=515&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342278
  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/515.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/515/head:pull/515

PR: https://git.openjdk.org/shenandoah/pull/515