[crac] RFR: 8368570: [CRaC] Improve JdwpTransportTest [v3]

[Roman Marchenko]

> JdwpTransportTest sometimes hangs, so it'd be good to dump Java threads, and create a corefile if possible.
> 
> Also improved reading from output stream.

Roman Marchenko has updated the pull request incrementally with one additional commit since the last revision:

  fix review comments

-------------

Changes:
  - all: https://git.openjdk.org/crac/pull/265/files
  - new: https://git.openjdk.org/crac/pull/265/files/9573ebf9..c40c1be7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=265&range=02
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=265&range=01-02

  Stats: 45 lines in 3 files changed: 36 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/crac/pull/265.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/265/head:pull/265

PR: https://git.openjdk.org/crac/pull/265