RFR: 8254861: reformat code in vmTestbase/nsk/jdb

[Igor Ignatyev]

Hi all,

could you please review this patch which reformats/cleans up the code of vmTestbase/nsk/jdb tests?

the part of this patch is a spinoff from #350.

testing:
* [x] `vmTestbase/nsk/jdb` tests on `linux-x64-debug`

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Commit messages:
 - 8254861: reformat code in vmTestbase/nsk/jdb

Changes: https://git.openjdk.java.net/jdk/pull/689/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=689&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254861
  Stats: 3829 lines in 130 files changed: 572 ins; 489 del; 2768 mod
  Patch: https://git.openjdk.java.net/jdk/pull/689.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/689/head:pull/689

PR: https://git.openjdk.java.net/jdk/pull/689