Continue to complete PR #16006 and PR #21593 to improve BigDecimal::toString and BigDecimal::toPlainString performance and reduce duplicate code
------------- Commit messages: - simplify and comments - simplify - simplify - code style - revert change - bug fix - bug fix - refactor - Revert "simplify scale2" - simplify scale2 - ... and 15 more: https://git.openjdk.org/jdk/compare/f446cefe...cb88e0ef Changes: https://git.openjdk.org/jdk/pull/23310/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23310&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8315585 Stats: 448 lines in 3 files changed: 237 ins; 118 del; 93 mod Patch: https://git.openjdk.org/jdk/pull/23310.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/23310/head:pull/23310 PR: https://git.openjdk.org/jdk/pull/23310
