<!-- Add the related story/sub-task/bug number, like Resolves#123, or
remove if NA -->
**Related issue:** Resolves#42799
When a macOS device acknowledges a lock command it can immediately send
a trailing Idle check-in. CleanAppleMDMLock now requires that unlock_ref
to be set at least 5 minutes ago before clearing the lock state,
preventing that trailing Idle to prematurely clearing the MDM lock
state.