RFR: 8368156: java/nio/file/Files/IsSameFile.java failing (win)

[Brian Burkhalter]

Use try-with-resources to ensure that the FileSystem `zipfs` is closed when no longer needed. This fixes the issue at hand. Other changes are to simplify cleanup of test files.

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Commit messages:
 - 8368156: Simplify cleanup of test files
 - 8368156: java/nio/file/Files/IsSameFile.java failing (win)

Changes: https://git.openjdk.org/jdk/pull/27440/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27440&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368156
  Stats: 57 lines in 1 file changed: 3 ins; 24 del; 30 mod
  Patch: https://git.openjdk.org/jdk/pull/27440.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27440/head:pull/27440

PR: https://git.openjdk.org/jdk/pull/27440