RFR: 8371721: Refactor checkTrusted methods in X509TrustManagerImpl [v4]

[Artur Barashev]

> The 3 checkTrusted methods in X509TrustManagerImpl have a lot of repeating code that can be moved into a helper method.

Artur Barashev has updated the pull request incrementally with one additional commit since the last revision:

  Only the last few sentences of javadoc are outdated

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28275/files
  - new: https://git.openjdk.org/jdk/pull/28275/files/0cabd3c4..f9233a75

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28275&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28275&range=02-03

  Stats: 9 lines in 1 file changed: 9 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28275.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28275/head:pull/28275

PR: https://git.openjdk.org/jdk/pull/28275