Microsoft.Data.SqlClient.ConnectionPool.NoOpAcquiredLease
A no-op RateLimitLease that is always acquired and performs no work on
dispose. Used as a stand-in when no rate limiter is configured so the open path can
treat the lease as unconditional. Stateless and safe to share across all callers; access
the singleton via Instance.
The shared singleton instance. Because it is stateless and its Dispose
releases nothing, the same instance is handed to every caller that opens without a
configured limiter and may be disposed any number of times, on any thread, without
affecting other callers.