RFR: 8287785: Reduce runtime of java.lang.invoke microbenchmarks

[Claes Redestad]

- Add explicit run configurations to java.lang.invoke micros, aiming to reduce runtime while maintaining a decently high confidence that there's enough warmup to produce good enough data.

- Remove several trivial baseline micros, mainly those that only return a static object: It's reasonable to have baseline microbenchmarks when the baseline op is complex and you're mostly interested in checking the overhead of doing the same thing via some MH API, but blackhole operations are now shortcutting very quickly and timings doesn't differ from one type of object to another, so we don't need a multitude of such baseline tests.

Estimated runtime of `make test TEST=micro:java.lang.micro` (excluding build) drops from just above 28 to just above 3 hours.

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Commit messages:
 - 8287785: Apply explicit run configuration to java.lang.invoke microbenchmarks

Changes: https://git.openjdk.java.net/jdk/pull/9012/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9012&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287785
  Stats: 429 lines in 47 files changed: 276 ins; 142 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/9012.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/9012/head:pull/9012

PR: https://git.openjdk.java.net/jdk/pull/9012