RFR: 8370633: Remove dead code for Windows file path canonicalization functions

[Brian Burkhalter]

Remove the unused, vestigial functions `wcanonicalizeWithPrefix` and `Java_java_io_WinNTFileSystem_canonicalizeWithPrefix0`. With this change, the build in the CI succeeds on Windows.

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Commit messages:
 - 8370633: Remove dead code for Windows file path canonicalization functions

Changes: https://git.openjdk.org/jdk/pull/27981/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27981&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370633
  Stats: 94 lines in 2 files changed: 0 ins; 94 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27981.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27981/head:pull/27981

PR: https://git.openjdk.org/jdk/pull/27981