Introduced a module-level flag _audit_subscriber_initialized to track
whether audit_event_subscriber() has been successfully called. When
get_container() is invoked and the flag is False, the subscriber
initialization is reattempted regardless of whether _container already
exists. On success the flag is set to True so no further attempts
are made; on failure the warning is logged and the flag remains False
so the next get_container() call retries.
Previously, a failed audit subscriber init during the first
get_container() call was permanently cached: _container was set but
the subscriber was never retried. In CLI mode this is masked because
each invocation is a new process, but in long-lived server processes
the audit subscriber would remain unregistered for the process
lifetime.
Also brings in the TDD regression test from issue #1096 (branch
tdd/m6-di-audit-cache-failure) with the @tdd_expected_fail tag
removed, converting it to a normal passing regression guard. Added
an ASV benchmark measuring retry-path performance.
ISSUES CLOSED: #992
brent.edwards