RFR: 8337838: Remove unused methods from ChronoLocalDateImpl

[Andrey Turbanov]

A few methods in `java.time.chrono.ChronoLocalDateImpl` are unused and could be removed:
1. plusWeeks(long)
2. minusYears(long)
3. minusMonths(long)
4. minusWeeks(long)
5. minusDays(long)

Tested `test/jdk/java/time` on Linux x64 release

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Commit messages:
 - [PATCH] Remove unused methods from ChronoLocalDateImpl

Changes: https://git.openjdk.org/jdk/pull/20250/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20250&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337838
  Stats: 203 lines in 5 files changed: 0 ins; 198 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/20250.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20250/head:pull/20250

PR: https://git.openjdk.org/jdk/pull/20250