RFR: 8269302: serviceability/dcmd/framework/InvalidCommandTest.java still fails after JDK-8268433

[Alex Menkov]

Please review this trivial fix in the cycle condition.

The cycle should run until connection is established (connection.isConnected() returns true) or error occurred (error != null)
This wrong condition causes test error if ListenerThread.getConnection() reaches "synchronized (this)" section earlier than ListenerThread.run()

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Commit messages:
 - Fixed cycle condition in ListenerThread.getConnection

Changes: https://git.openjdk.java.net/jdk/pull/4593/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4593&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269302
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4593.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4593/head:pull/4593

PR: https://git.openjdk.java.net/jdk/pull/4593