[jdk17u] RFR: 8272369: java/io/File/GetXSpace.java failed with "RuntimeException: java.nio.file.NoSuchFileException: /run/user/0"

[Alex Kasko]

Clean backport of a test fix,

Additional testing:

 - [x] checked that upated test passes on Linux, Windows and Mac. Was unable to reproduce the failure without the patch

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Commit messages:
 - Backport a68b5b9c1dd9dd69fa3ef29d8f1186707ec09311

Changes: https://git.openjdk.java.net/jdk17u/pull/249/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=249&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272369
  Stats: 19 lines in 1 file changed: 11 ins; 4 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/249.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/249/head:pull/249

PR: https://git.openjdk.java.net/jdk17u/pull/249