RFR: 8334726: Remove accidentally exposed individual methods from Class-File API

[Chen Liang]

In preparation of Class-File API exiting review, we are housekeeping our API surface. These 3 method removals are the most obvious and simple ones.

This is separated from more throughout and (possibly controversial) changes for the future, to make reviews (both code and CSR) easier.

-------------

Commit messages:
 - 8334726: Remove accidentally exposed individual methods from Class-File API

Changes: https://git.openjdk.org/jdk/pull/19832/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19832&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334726
  Stats: 37 lines in 7 files changed: 0 ins; 30 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/19832.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19832/head:pull/19832

PR: https://git.openjdk.org/jdk/pull/19832