DO NOT MERGE Cherry-pick: ICU-20536 Japanese era Reiwa support in ICU4J 58

Partial cherry-pick https://github.com/unicode-org/icu/commit/913b5e8f5dbbe8ddca19c221f9867c00a9d84b94
- Exclude non-test files

Update android_icu4j by running tools/srcgen/generate_android_icu4j.sh

Bug: 138560701
Test: CtsIcuTestCases
Test: CtsLibcoreTestCases
Test: CtsLibcoreOjTestCases
Change-Id: If5d3468e5dbd2b90435f0b23528cbe3d3b4c42a8
5 files changed