RFR: 8331646: Add specific regression leap year tests [v5]

[serhiysachkov]

> Calendar.add() tests that describe its behavior.

serhiysachkov has updated the pull request incrementally with one additional commit since the last revision:

  JDK-8331646 fixing typo

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19082/files
  - new: https://git.openjdk.org/jdk/pull/19082/files/f6ba2e31..8e070b4e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19082&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19082&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19082.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19082/head:pull/19082

PR: https://git.openjdk.org/jdk/pull/19082