asim: use << 20 instead of 1024*1024

This commit updates defaultRangeSizeSplitThreshold to use bit shifting instead
of multiplication for convention.

Epic: none
Release note: none

Author: wenyihu6

pkg/kv/kvserver/asim/config/settings.go

@@ -13,7 +13,7 @@ const (
 	defaultReplicaChangeBaseDelay  = 100 * time.Millisecond
 	defaultRebalancingSnapshotRate = 32 << 20 // 32MiB/s
 	defaultSplitQueueDelay         = 100 * time.Millisecond
-	defaultRangeSizeSplitThreshold = 512 * 1024 * 1024 // 512mb
+	defaultRangeSizeSplitThreshold = 512 << 20 // 512MiB
 	defaultRangeRebalanceThreshold = 0.05
 	defaultPacerLoopInterval       = 10 * time.Minute
 	defaultPacerMinIterInterval    = 10 * time.Millisecond