Consolidate class-level error record finalization in BaseTestClass

[xpconanfan]

Summary

Fixes #1029.

Consolidates all 6 class-level error record finalization sites (_pre_run, _setup_class exception & expects branches, _teardown_class exception & expects branches, and _clean_up) into a single helper method BaseTestClass._record_class_error().

Problem

1. Lost class error records on abort_all() in on_fail (Issue setup_class error record is not written to test_summary.yaml when on_fail raises TestAbortAll #1029):
   When setup_class fails (via an uncaught exception or expects) and on_fail raises an abort signal (asserts.abort_all() / asserts.abort_class()), summary_writer.dump() (and results.add_class_error() in the expects path) were skipped because they appeared after self._exec_procedure_func(self._on_fail, class_record) without a try...finally guard.
2. Missing end_time and details inside on_fail for setup_class expects failures:
   In _setup_class, the if expects.recorder.has_error: block previously invoked self._exec_procedure_func(self._on_fail, class_record) before class_record.test_error() and class_record.update_record(). As a result, record.end_time and record.details were None inside on_fail (unlike normal test failures in exec_one_test or uncaught exceptions in _setup_class).

Solution

Introduce _record_class_error(self, record, e=None, exec_on_fail=False) which enforces a canonical lifecycle across all class stages:

1. Call record.test_error(e) and record.update_record() before running on_fail so record.end_time, record.termination_signal, and record.details are always populated when on_fail executes.
2. Execute _exec_procedure_func(self._on_fail, record) inside a try...finally block so that self.results.add_class_error(record) and self.summary_writer.dump(...) always execute even if on_fail raises an abort signal.

[hjfreyer]

I've confirmed that this resolves my issue! Thanks!