kvserver: make PriorityInversionRequeue and ReplicateQueueMaxSize metamorphic

Previously, we introduced the cluster settings PriorityInversionRequeue and
ReplicateQueueMaxSize, defaulting them to true and math.MaxInt64 on master but
keeping them disabled and defaultQueueMaxSize on release branches. To allow
additional bake time in release branches, this commit makes both settings
metamorphic on the release branches.

Author: wenyihu6

pkg/kv/kvserver/replicate_queue.go

@@ -8,6 +8,7 @@ package kvserver
 import (
 	"context"
 	"fmt"
+	"math"
 	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/gossip"
@@ -24,6 +25,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/spanconfig"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/metamorphic"
 	"github.com/cockroachdb/cockroach/pkg/util/metric"
 	"github.com/cockroachdb/cockroach/pkg/util/retry"
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
@@ -111,19 +113,21 @@ var PriorityInversionRequeue = settings.RegisterBoolSetting(
 	"kv.priority_inversion_requeue_replicate_queue.enabled",
 	"whether the requeue replicas should requeue when enqueued for "+
 		"repair action but ended up consider rebalancing during processing",
-	false,
+	metamorphic.ConstantWithTestBool("kv.priority_inversion_requeue_replicate_queue.enabled",
+		false /*defaultValue*/),
 )
 
 // ReplicateQueueMaxSize is a setting that controls the max size of the
 // replicate queue. When this limit is exceeded, lower priority replicas (not
 // guaranteed to be the lowest) are dropped from the queue.
 var ReplicateQueueMaxSize = settings.RegisterIntSetting(
-	settings.ApplicationLevel,
+	settings.SystemOnly,
 	"kv.replicate_queue.max_size",
 	"maximum number of replicas that can be queued for replicate queue processing; "+
 		"when this limit is exceeded, lower priority (not guaranteed to be the lowest) "+
 		"replicas are dropped from the queue",
-	defaultQueueMaxSize,
+	metamorphic.ConstantWithTestChoice[int64]("kv.replicate_queue.max_size",
+		defaultQueueMaxSize /*defaultValue*/, math.MaxInt32 /*otherValues*/),
 	settings.WithValidateInt(func(v int64) error {
 		if v < defaultQueueMaxSize {
 			return errors.Errorf("cannot be set to a value lower than %d: %d", defaultQueueMaxSize, v)