RFR: 8343395: SSLLogger doesn't work for formatted messages

[Sean Coffey]

SLSLogger is broken when used with with `System.Logger` (-Djavax.net.debug mode)

SSL Debug messages don't use format specifiers. As a result, any custom format data isn't printed. Proposed solution is to append the SSL custom format output to the original debug message. Similar approach used for `SSLConsoleLogger ` mode.

Used this opportunity to delete some old commented code and to replace use of `"\n"` with `System.lineSeparator()`

DebugPropertyValuesTest also updated to test new logic.

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

Commit messages:
 - 8343395

Changes: https://git.openjdk.org/jdk/pull/25934/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25934&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343395
  Stats: 28 lines in 2 files changed: 7 ins; 10 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/25934.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25934/head:pull/25934

PR: https://git.openjdk.org/jdk/pull/25934