RFR: JDK-8195809: [TESTBUG] jps and jcmd -l support for containers is not tested [v2]

[Mikhailo Seledtsov]

> Please review this addition of new testing:
>   - new test for sending jcmd commands across container boundaries
>   - updated existing sidecar test, enabling jcmd test case

Mikhailo Seledtsov has updated the pull request incrementally with one additional commit since the last revision:

  Updated comment

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5368/files
  - new: https://git.openjdk.java.net/jdk/pull/5368/files/b714f662..1a66f1c0

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5368&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5368&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5368.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5368/head:pull/5368

PR: https://git.openjdk.java.net/jdk/pull/5368