RFR: 8288568: Reduce runtime of java.security microbenchmarks

[Claes Redestad]

- Reduce forks, iteration, runtime to reduce runtime while maintaining high data quality on typical benchmarking hosts.

Reduces runtime from estimated 10+ hours to 54 minutes.

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Commit messages:
 - Reduce runtime of java.security microbenchmarks

Changes: https://git.openjdk.org/jdk/pull/9189/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9189&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288568
  Stats: 39 lines in 9 files changed: 25 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/9189.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9189/head:pull/9189

PR: https://git.openjdk.org/jdk/pull/9189