refactor(reforcexy): deduplicate Optuna-artifact quarantine machinery

refactor(reforcexy): deduplicate Optuna-artifact quarantine machinery

Review follow-up (DRY, single-source-of-truth). The best-params
quarantine re-inlined the timestamp + tie-break path computation already
provided by _quarantine_path, and duplicated the journal quarantine
tag/limit constants with identical values.

- Reuse _quarantine_path from _quarantine_corrupt_best_trial_params;
  the wrapper keeps its own pair-prefixed logging and rename error
  handling, so both call sites' log output and error semantics are
  unchanged.
- Collapse _JOURNAL_QUARANTINE_TAG/_BEST_PARAMS_QUARANTINE_TAG and their
  tie-break limits into neutral shared _QUARANTINE_TAG /
  _QUARANTINE_TIE_BREAK_LIMIT (same values: "corrupt" / 99); generalize
  the _quarantine_path parameter name journal_path -> path.
- Regroup the constants so the _JOURNAL_* block stays contiguous, with
  the shared quarantine constants after it.