RFR: 8213714: AttachingConnector/attach/attach001 failed due to "bind failed: Address already in use"

[Alex Menkov]

The fix updates the tests to use dynamic port launching debuggee and get the listening port from the debugee output

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Commit messages:
 - Fixed AttachingConnector tests

Changes: https://git.openjdk.java.net/jdk/pull/4817/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4817&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8213714
  Stats: 130 lines in 4 files changed: 63 ins; 41 del; 26 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4817.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4817/head:pull/4817

PR: https://git.openjdk.java.net/jdk/pull/4817