RFR: 8208237: Re-examine defmeth tests and update as needed [v2]

[Vladimir Ivanov]

> Some test cleanups:
> - removed all `@KnownFailure`
> - narrowed expected error types in some cases
> - fixed private method invocation tests in reflection mode (got rid of `NoSuchMethodError`s in reflection mode)
> - introduced `TesterBuilder::new_()` to let the tests precisely describe the intent
> - some other minor cleanups
> 
> Testing:
> - [x] defmeth tests
> - [x] hs-tier5 - hs-tier6 (include defmeth tests)

Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  Adjust year in copyright

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3879/files
  - new: https://git.openjdk.java.net/jdk/pull/3879/files/32ee955e..78fb2851

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3879&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3879&range=00-01

  Stats: 16 lines in 16 files changed: 0 ins; 0 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3879.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3879/head:pull/3879

PR: https://git.openjdk.java.net/jdk/pull/3879