region fit rule should run once.

[bufferflies]

In past, the SelectOneRegion function has fit the region rule , then the NewPlacementSafeguard also fit it.

some relate code:

pd/server/schedule/filter/region_filters.go

Lines 104 to 115 in 0433eea

	func (f *regionReplicatedFilter) Select(region *core.RegionInfo) *plan.Status {
	if f.cluster.GetOpts().IsPlacementRulesEnabled() {
	if !isRegionPlacementRuleSatisfied(f.cluster, region) {
	return statusRegionNotMatchRule
	}
	return statusOK
	}
	if !isRegionReplicasSatisfied(f.cluster, region) {
	return statusRegionNotReplicated
	}
	return statusOK
	}