allocator: add cluster setting to disable lease transfers

**Is your feature request related to a problem? Please describe.**
Currently, there are different cluster settings to disable [store rebalancer (cpu/qps) lease transfers](https://github.com/cockroachdb/cockroach/blob/b5cef207d5b5905f8a845da5795f1231c7c7545c/pkg/kv/kvserver/store_rebalancer.go#L75-L75), follow-the-workload lease transfers and to [reduce the lease transfer interval of the replicate queue](https://github.com/cockroachdb/cockroach/blob/b5cef207d5b5905f8a845da5795f1231c7c7545c/pkg/kv/kvserver/replicate_queue.go#L97-L97).

There isn't a method to outright disable all of these, or alternatively disable lease count rebalancing.

**Describe the solution you'd like**
Add a cluster setting to disable all allocator lease transfers, except those explicitly required such as drain/decommission.

Jira issue: CRDB-31586