CRM_Queue_Queue_* - Respect `$queueSpec['lease_time']` (if given)

CRM_Queue_Queue_* - Respect `$queueSpec['lease_time']` (if given)

Before: The lease-time is one of the following:

1. A value requested at runtime
2. The constant 3600

After: The lease-time is either supplied as

1. A value requested at runtime
2. A value configured for the queue
3. The constant 3600