RFR: 8353738: Update TLS unit tests to not use certificates with MD5 signatures

[Matthew Donovan]

This PR updates tests that were using MD5 certificates. For most of the tests, I added test cases for TLSv1.2/MD5withRSA and TLSv1.3/SHA256withRSA.

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Commit messages:
 - 8353738: Update TLS unit tests to not use certificates with MD5 signatures

Changes: https://git.openjdk.org/jdk/pull/27342/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27342&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8353738
  Stats: 2551 lines in 10 files changed: 400 ins; 2046 del; 105 mod
  Patch: https://git.openjdk.org/jdk/pull/27342.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27342/head:pull/27342

PR: https://git.openjdk.org/jdk/pull/27342