BUG/MINOR: queue/debug: use the correct lock labels on the queue lock

A dedicated queue lock was added by commit 16fbdda3c ("MEDIUM: queue:
use a dedicated lock for the queues (v2)") but during its rebase, some
labels were lost and left to SERVER_LOCK / PROXY_LOCK instead of
QUEUE_LOCK. It's harmless but can confuse the lock debugger, so better
fix it.

No backport is needed.
1 file changed