Fix DBIx::Class ordered test CODE weaken GC stall

[fglock]

Summary

• Avoid running a full weak-ref reachability sweep from the hot weaken(CODE) path.
• Keep the existing CODE-specific stale weak-ref cleanup for expired anonymous or former-stash CODE refs.
• Fixes the DBIx::Class t/87ordered.t stall caused by repeated explicit old-GC cycles.

Investigation

jstack on the stuck t/87ordered.t child showed the main thread inside:

Runtime.gc
ScalarRefRegistry.forceGcAndSnapshot
ReachabilityWalker.sweepWeakRefs
WeakRefRegistry.weaken
Scalar::Util::weaken
DBIx::Class::Storage::BlockRunner

JFR confirmed the process was not blocked in SQL or DBIC logic: a 20s recording had 519 System.gc() / old-GC events.

Verification

• make
• timeout 120 ./jperl src/test/resources/unit/refcount/subquote_defer_weak_cleanup.t
• timeout 120 ./jperl src/test/resources/unit/refcount/weaken_closure_argument.t
• timeout 600 ./jperl -Iblib/lib -Iblib/arch t/87ordered.t from the DBIx-Class build dir

The direct DBIC check passed 1..1271 with Auto checked 5 references for leaks - none detected.