RFR: 8338471: Refactor Method::get_new_method() for better NoSuchMethodError handling

[Matias Saavedra Silva]

This patch cleans up the use of `get_new_method()` so callers don't have to worry about throwing `NoSuchMethodError`. The method is refactored to throw the error and avoid ever returning nullptr. Verified with tier1-5 tests.

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Commit messages:
 - 8338471: Refactor Method::get_new_method() for better NoSuchMethodError handling

Changes: https://git.openjdk.org/jdk/pull/20874/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20874&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338471
  Stats: 11 lines in 3 files changed: 1 ins; 6 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/20874.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20874/head:pull/20874

PR: https://git.openjdk.org/jdk/pull/20874