refactor: update default pruning strategy (#9859)

The `default` pruning strategy, specifically the total number of recent blocks to keep (currently 100), was decided on completely arbitrary. 

I propose we change it to be enough blocks given that the typical block time is 5s and typical unbonding period is 21 days:
(3600*(24/5)) * 21 = 362880.

I propose this because anyone wishing to run an IBC relayer, which will be most chains, will have to be required to use `custom` to set it to this value anyway. So why not just make it the default and make it easier for operators.

---

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store/types/pruning.go

@@ -11,10 +11,12 @@ const (
 )
 
 var (
-	// PruneDefault defines a pruning strategy where the last 100 heights are kept
-	// in addition to every 100th and where to-be pruned heights are pruned at
-	// every 10th height.
-	PruneDefault = NewPruningOptions(100, 100, 10)
+	// PruneDefault defines a pruning strategy where the last 362880 heights are
+	// kept in addition to every 100th and where to-be pruned heights are pruned
+	// at every 10th height. The last 362880 heights are kept assuming the typical
+	// block time is 5s and typical unbonding period is 21 days. If these values
+	// do not match the applications' requirements, use the "custom" option.
+	PruneDefault = NewPruningOptions(362880, 100, 10)
 
 	// PruneEverything defines a pruning strategy where all committed heights are
 	// deleted, storing only the current height and where to-be pruned heights are