RFR: 8291828: Reduce runtime of java.util.stream microbenchmarks [v2]

[Eric Caspole]

> These changes reduce the default run time from about 1 day 22 hours to about 6 hours with good stability we can use in weekly testing.

Eric Caspole has updated the pull request incrementally with one additional commit since the last revision:

  Clean up imports and shorten run time preserving result stability

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9733/files
  - new: https://git.openjdk.org/jdk/pull/9733/files/b5ee0670..fd244b64

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9733&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9733&range=00-01

  Stats: 10 lines in 2 files changed: 0 ins; 4 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/9733.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9733/head:pull/9733

PR: https://git.openjdk.org/jdk/pull/9733