spread OSDs across zones uniformly

issue:
- consider we have three nodes in a zone and one of the nodes (bigger) which is
  cordoned has 5 OSDs running, two other nodes (smaller) are not running OSDs
- assume the region has three such zones in same config
- now if we evict OSDs from the cordoned node and have tsc at hostname
  level to satisfy the constraint all OSDs should be running on one of
  smaller nodes which isn't possible due to less resources
- due to this we can't ever evict pods from the bigger node if tsc takes
  into account of cordoned nodes as well

rc:
- we don't have a way to take tainted nodes into consideration in tsc
  calculations until k8s 1.26 [0]

fix:
- set tsc at zone level which effectively counts number of OSDs running
  per zone even with cordon nodes
- as a result we can have 5 OSDs running in a zone irrespective of
  bigger/smaller nodes

[0]: kubernetes/enhancements/pull/3105

Signed-off-by: Leela Venkaiah G <lgangava@redhat.com>

templates/providerstoragecluster.go

@@ -35,7 +35,7 @@ const (
 
 var commonTSC corev1.TopologySpreadConstraint = corev1.TopologySpreadConstraint{
 	MaxSkew:           1,
-	TopologyKey:       "kubernetes.io/hostname",
+	TopologyKey:       "topology.kubernetes.io/zone",
 	WhenUnsatisfiable: corev1.DoNotSchedule,
 	LabelSelector: &metav1.LabelSelector{
 		MatchExpressions: []metav1.LabelSelectorRequirement{
@@ -50,7 +50,7 @@ var commonTSC corev1.TopologySpreadConstraint = corev1.TopologySpreadConstraint{
 
 var preparePlacementTSC corev1.TopologySpreadConstraint = corev1.TopologySpreadConstraint{
 	MaxSkew:           1,
-	TopologyKey:       "topology.kubernetes.io/zone",
+	TopologyKey:       "kubernetes.io/hostname",
 	WhenUnsatisfiable: corev1.DoNotSchedule,
 	LabelSelector: &metav1.LabelSelector{
 		MatchExpressions: []metav1.LabelSelectorRequirement{