RFR: 7903495: jcstress: Generated test actors should not request the result when not needed

[Aleksey Shipilev]

Many @Actor-s in generated tests do not actually require a result. Avoiding the unnecessary result load optimizes the interpreter and C1.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jcstress/pull/141/files
 Webrev: https://webrevs.openjdk.org/?repo=jcstress&pr=141&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903495
  Stats: 6 lines in 2 files changed: 3 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jcstress/pull/141.diff
  Fetch: git fetch https://git.openjdk.org/jcstress.git pull/141/head:pull/141

PR: https://git.openjdk.org/jcstress/pull/141