[crac] RFR: 8377562: [CRaC] Add better logging to RemoteJmxTest

[Timofei Pushkin]

Makes `RemoteJmxTest` log stderr of the child process.

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Commit messages:
 - Add better logging to RemoteJmxTest

Changes: https://git.openjdk.org/crac/pull/295/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=295&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377562
  Stats: 34 lines in 1 file changed: 16 ins; 12 del; 6 mod
  Patch: https://git.openjdk.org/crac/pull/295.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/295/head:pull/295

PR: https://git.openjdk.org/crac/pull/295