[jdk8u-dev] RFR: 8335894: [8u] Fix SupplementalJapaneseEraTest.java for jdks with symlinked conf dir

[SendaoYan]

Hi all,
Fix the testcase bug, which if the tested jdk directory is symlinked, symlinks are followed when copying tested jdk.
This is similar to [JDK-8309138](https://bugs.openjdk.org/browse/JDK-8309138).
Only change the testcase, the change has been verified, no risk.

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Commit messages:
 - 8335894: [8u] Fix SupplementalJapaneseEraTest.java for jdks with symlinked conf dir

Changes: https://git.openjdk.org/jdk8u-dev/pull/542/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=542&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335894
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/542.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/542/head:pull/542

PR: https://git.openjdk.org/jdk8u-dev/pull/542