admission: turn on snapshot ingest bandwidth control by default

With cockroachdb#133310 merged, and
promising results from internal experimentation, we can turn this
setting on by default.

Informs: cockroachdb#121779.

Release note (ops change):
`kvadmission.store.snapshot_ingest_bandwidth_control.enabled` is now
'true' by default. This will enable disk bandwdith based Admission
Control for range snapshot ingests. It requires the provisioned
bandwidth to be set using `kvadmission.store.provisioned_bandwidth`.

pkg/util/admission/snapshot_queue.go

@@ -49,8 +49,7 @@ var snapshotWorkItemPool = sync.Pool{
 var DiskBandwidthForSnapshotIngest = settings.RegisterBoolSetting(
 	settings.SystemOnly, "kvadmission.store.snapshot_ingest_bandwidth_control.enabled",
 	"if set to true, snapshot ingests will be subject to disk write control in AC",
-	// TODO(aaditya): Enable by default once enough experimentation is done.
-	metamorphic.ConstantWithTestBool("kvadmission.store.snapshot_ingest_bandwidth_control.enabled", false),
+	metamorphic.ConstantWithTestBool("kvadmission.store.snapshot_ingest_bandwidth_control.enabled", true),
 	settings.WithPublic,
 )