RFR: 8361253: CommanLineOptionTest library should report observed values on failure

[Manuel Hässig]

When a check in `CommandLineOptionTest` fails, the `AssertionError` message contains the expected value, but not the observed value. To reduce the amount of digging in the logs we have to do when analyzing a failure, this PR adds the observed value to the error messages. So instead of 


java.lang.AssertionError: Option 'CICompilerCount' is expected to have '12' value


a mismatch in the `CICompilerCount` will now print


java.lang.AssertionError: Option 'CICompilerCount' is expected to have '12' value, but is 'CICompilerCount = 6'.


Testing:
 - [ ] Github Actions
 - [ ] tier1 through tier3 plus Oracle internal testing

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Commit messages:
 - Add observed values to CommandLineOptionTest error messages

Changes: https://git.openjdk.org/jdk/pull/26092/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26092&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361253
  Stats: 7 lines in 1 file changed: 3 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/26092.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26092/head:pull/26092

PR: https://git.openjdk.org/jdk/pull/26092