[jdk11u-dev] RFR: 8235211: serviceability/attach/RemovingUnixDomainSocketTest.java fails with AttachNotSupportedException: Unable to open socket file

[Martin Doerr]

Clean backport of JDK-8235211. Test backport is not clean. I had to integrate it manually and add the simple change JDK-8244973 because `out.stderrShouldBeEmptyIgnoreVMWarnings().stderrShouldBeEmpty();` is neither correct, nor supported in 11u.

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Commit messages:
 - Add fix for JDK-8244973.
 - Backport 073e095e6053550b17b1daf33df2be4f4c4b40ad

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/153/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=153&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8235211
  Stats: 70 lines in 5 files changed: 37 ins; 2 del; 31 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/153.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/153/head:pull/153

PR: https://git.openjdk.java.net/jdk11u-dev/pull/153