<i18n dev> RFR: JDK-8316559: Refactor some util/Calendar tests to JUnit [v2]

[Justin Lu]

> 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.

Justin Lu has updated the pull request incrementally with two additional commits since the last revision:

 - Review: revert removal of SupressWarnings annotation
 - Reflect review comments

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15853/files
  - new: https://git.openjdk.org/jdk/pull/15853/files/43e17eb8..a0cfa852

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15853&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15853&range=00-01

  Stats: 51 lines in 7 files changed: 35 ins; 1 del; 15 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