kvserver,asim: move storepool ownership out of allocator

This fully decouples the StorePool from the allocator by moving
ownership of the configured view of peer stores to the store
configuration (the original source), the store rebalancer, and various
structures in the allocator simulator.

Part of #91570.

Release note: None

pkg/kv/kvserver/allocator/allocatorimpl/allocator.go

@@ -479,7 +479,6 @@ type AllocatorMetrics struct {
 type Allocator struct {
 	st            *cluster.Settings
 	deterministic bool
-	StorePool     storepool.AllocatorStorePool
 	nodeLatencyFn func(addr string) (time.Duration, bool)
 	// TODO(aayush): Let's replace this with a *rand.Rand that has a rand.Source
 	// wrapped inside a mutex, to avoid misuse.
@@ -509,28 +508,26 @@ func makeAllocatorMetrics() AllocatorMetrics {
 	}
 }
 
-// MakeAllocator creates a new allocator using the specified StorePool.
+// MakeAllocator creates a new allocator.
+// The deterministic flag indicates that this allocator is intended to be used
+// with a deterministic store pool.
+//
+// In test cases where the store pool is nil, deterministic should be false.
 func MakeAllocator(
 	st *cluster.Settings,
-	storePool storepool.AllocatorStorePool,
+	deterministic bool,
 	nodeLatencyFn func(addr string) (time.Duration, bool),
 	knobs *allocator.TestingKnobs,
 ) Allocator {
 	var randSource rand.Source
-	var deterministic bool
-	// There are number of test cases that make a test store but don't add
-	// gossip or a store pool. So we can't rely on the existence of the
-	// store pool in those cases.
-	if storePool != nil && storePool.IsDeterministic() {
+	if deterministic {
 		randSource = rand.NewSource(777)
-		deterministic = true
 	} else {
 		randSource = rand.NewSource(rand.Int63())
 	}
 	allocator := Allocator{
 		st:            st,
 		deterministic: deterministic,
-		StorePool:     storePool,
 		nodeLatencyFn: nodeLatencyFn,
 		randGen:       makeAllocatorRand(randSource),
 		Metrics:       makeAllocatorMetrics(),
@@ -2349,7 +2346,9 @@ func (a Allocator) shouldTransferLeaseForLeaseCountConvergence(
 // PreferredLeaseholders returns a slice of replica descriptors corresponding to
 // replicas that meet lease preferences (among the `existing` replicas).
 func (a Allocator) PreferredLeaseholders(
-	storePool storepool.AllocatorStorePool, conf roachpb.SpanConfig, existing []roachpb.ReplicaDescriptor,
+	storePool storepool.AllocatorStorePool,
+	conf roachpb.SpanConfig,
+	existing []roachpb.ReplicaDescriptor,
 ) []roachpb.ReplicaDescriptor {
 	// Go one preference at a time. As soon as we've found replicas that match a
 	// preference, we don't need to look at the later preferences, because