storage: de-flake TestReplicaLeaseCounters
storage: de-flake TestReplicaLeaseCounters

The main reason for failures were racing LeaderLease requests, but more
generally a lack of replay protection was causing this test to fail when Raft
reproposals would happen, usually within <100 iterations. Now:

> 5303 runs so far, 0 failures, over 40s

Fixes #6420.

paperstreet/cockroach,cockroachdb/cockroach,vivekmenezes/cockroach,sunya123/cockroach,petermattis/cockroach,vivekmenezes/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,petermattis/cockroach,glycerine/cockroach,maxlang/cockroach,glycerine/cockroach,vaibhavarora/cockroach,maxlang/cockroach,arjun4084346/cockroach,sunya123/cockroach,glycerine/cockroach,vivekmenezes/cockroach,vaibhavarora/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,cockroachdb/cockroach,glycerine/cockroach,veteranlu/cockroach,sunya123/cockroach,petermattis/cockroach,vaibhavarora/cockroach,arjun4084346/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,vaibhavarora/cockroach,maxlang/cockroach,paperstreet/cockroach,maxlang/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,petermattis/cockroach,glycerine/cockroach,petermattis/cockroach,vivekmenezes/cockroach,sunya123/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,vaibhavarora/cockroach,arjun4084346/cockroach,vaibhavarora/cockroach,glycerine/cockroach,glycerine/cockroach,veteranlu/cockroach,paperstreet/cockroach,glycerine/cockroach,veteranlu/cockroach,maxlang/cockroach,sunya123/cockroach,arjun4084346/cockroach,sunya123/cockroach,maxlang/cockroach,petermattis/cockroach,veteranlu/cockroach,arjun4084346/cockroach,paperstreet/cockroach,sunya123/cockroach,vivekmenezes/cockroach,veteranlu/cockroach,paperstreet/cockroach,petermattis/cockroach,vaibhavarora/cockroach,arjun4084346/cockroach,paperstreet/cockroach,petermattis/cockroach,cockroachdb/cockroach,maxlang/cockroach,paperstreet/cockroach,sunya123/cockroach,veteranlu/cockroach,maxlang/cockroach