RFR: 8376419: (fs) Minor improvement of java/nio/file/attribute/UserDefinedFileAttributeView/Basic.java

[Brian Burkhalter]

1. Use `RandomFactory` instead of `new Random` to allow reproducibility.
2. Use `jtreg.SkippedException` instead of printing a message and returning silently.

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Commit messages:
 - 8376419: (fs) Minor improvement of java/nio/file/attribute/UserDefinedFileAttributeView/Basic.java

Changes: https://git.openjdk.org/jdk/pull/29434/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29434&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376419
  Stats: 14 lines in 1 file changed: 5 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29434.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29434/head:pull/29434

PR: https://git.openjdk.org/jdk/pull/29434