RFR: JDK-8316559: Refactor some util/Calendar tests to JUnit

Wed Sep 20 23:27:51 UTC 2023

Please review this PR which converts some tests under _Calendar_ to use JUnit. These tests either previously used the internal _IntlTest_, or used no framework at all. 

Any files named BugXXXXXXX.java will be renamed after review.

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Commit messages:
 - Separate data generation and data testing in BuddhistCalendarTest
 - init

Changes: https://git.openjdk.org/jdk/pull/15853/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15853&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316559
  Stats: 679 lines in 10 files changed: 206 ins; 224 del; 249 mod
  Patch: https://git.openjdk.org/jdk/pull/15853.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15853/head:pull/15853

PR: https://git.openjdk.org/jdk/pull/15853