[#10741] fix(hive): Fix keytab symlink TOCTOU race in FetchFileUtils (#10742)

What changes were proposed in this pull request?

Fix the file: scheme handler in FetchFileUtils to synchronize symlink creation and avoid concurrent races. Replace the non-atomic exists() + delete() in KerberosClient with Files.deleteIfExists(). Remove the unused duplicate FetchFileUtils in catalog-hive and add comprehensive tests in hive-metastore-common.

Why are the changes needed?

Files.createSymbolicLink() throws FileAlreadyExistsException when multiple threads concurrently fetch the same keytab path, such as when the search event listener triggers cascade sync after catalog creation.

Fix: #10741

Does this PR introduce any user-facing change?

No.

How was this patch tested?

added unit coverage in TestFetchFileUtils including concurrent, idempotent, and target-replacement scenarios

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