fixup(golang/.../vstorage/keeper): report absolute values for metrics increase/decrease (#11101)

closes: #11062

## Description
We need to report absolute values for vstorage metrics increase/decrease as requested in #11063 (review)

### Security Considerations
N/A

### Scaling Considerations
N/A

### Documentation Considerations
`store_size_increase` and `store_size_decrease` metrics represent total writes and deletes *issued* respectively, which may differ from the total number of bytes committed/freed to/from the store due to the store's internal implementation.

### Testing Considerations
`vstorage metrics` test passed:
```
2025-03-11T16:06:25.744Z shutdown: Shutting down cleanly...
2025-03-11T16:06:25.745Z shutdown: Process terminated!
make: *** [Makefile:155: scenario2-run-chain] Error 98
  ✔ vstorage metrics (1m 14.8s)
    ℹ query vstorage path published.wallet.agoric1cuh05y5l2uhphv2995k5qhdg5crvs396ud7rv9 exits successfully
    ℹ metric start values: {
        'store_size_decrease{storeKey="vstorage"}': 1106,
        'store_size_increase{storeKey="vstorage"}': 1145,
      }
    ℹ query vstorage path published.wallet.agoric1cuh05y5l2uhphv2995k5qhdg5crvs396ud7rv9 exits successfully
    ℹ provisioned wallet agoric1cuh05y5l2uhphv2995k5qhdg5crvs396ud7rv9 is published
    ℹ metric stop values: {
        'store_size_decrease{storeKey="vstorage"}': 2180,
        'store_size_increase{storeKey="vstorage"}': 3585,
      }
  ─

  1 test passed
Done in 654.27s.
```

### Upgrade Considerations
N/A

Author: siarhei-agoric

golang/cosmos/x/vstorage/keeper/keeper.go

@@ -119,18 +119,24 @@ func NewKeeper(storeKey storetypes.StoreKey) Keeper {
 	}
 }
 
+// size_increase and size_decrease metrics represent total writes and deletes *issued*
+// respectively, which may differ from the total number of bytes committed/freed
+// to/from the store due to the store's internal implementation.
 var MetricKeyStoreSizeIncrease = []string{"store", "size_increase"}
-var MetricKeyStoreSizeDecrese = []string{"store", "size_decrease"}
+var MetricKeyStoreSizeDecrease = []string{"store", "size_decrease"}
 const MetricLabelStoreKey = "storeKey"
 
-func ReportStoreSizeMetrics(k Keeper, sizeDelta float32) {
+// reportStoreSizeMetrics exports store size increase/decrease metrics
+// when Cosmos telemetry is enabled.
+func (k Keeper) reportStoreSizeMetrics(increase int, decrease int) {
 	metricsLabel := []metrics.Label{
 		telemetry.NewLabel(MetricLabelStoreKey, k.storeKey.Name()),
 	}
-	if sizeDelta >= 0 {
-		telemetry.IncrCounterWithLabels(MetricKeyStoreSizeIncrease, sizeDelta, metricsLabel)
-	} else {
-		telemetry.IncrCounterWithLabels(MetricKeyStoreSizeDecrese, -sizeDelta, metricsLabel)
+	if increase > 0 {
+		telemetry.IncrCounterWithLabels(MetricKeyStoreSizeIncrease, float32(increase), metricsLabel)
+	}
+	if decrease > 0 {
+		telemetry.IncrCounterWithLabels(MetricKeyStoreSizeDecrease, float32(decrease), metricsLabel)
 	}
 }
 
@@ -233,8 +239,7 @@ func (k Keeper) RemoveEntriesWithPrefix(ctx sdk.Context, pathPrefix string) {
 
 	for _, key := range keys {
 		rawValue := store.Get(key)
-		sizeDelta := float32(-len(key) - len(rawValue))
-		ReportStoreSizeMetrics(k, sizeDelta)
+		k.reportStoreSizeMetrics(0, len(key) + len(rawValue))
 		store.Delete(key)
 	}
 
@@ -391,20 +396,17 @@ func (k Keeper) SetStorage(ctx sdk.Context, entry agoric.KVEntry) {
 	if !entry.HasValue() {
 		if !k.HasChildren(ctx, path) {
 			// We have no children, can delete.
-			sizeDelta := float32(-len(encodedKey) - len(oldRawValue))
-			ReportStoreSizeMetrics(k, sizeDelta)
+			k.reportStoreSizeMetrics(0, len(encodedKey) + len(oldRawValue))
 			store.Delete(encodedKey)
 		} else {
 			// We have children, mark as an empty placeholder without deleting.
-			sizeDelta := float32(len(types.EncodedNoDataValue) - len(oldRawValue))
-			ReportStoreSizeMetrics(k, sizeDelta)
+			k.reportStoreSizeMetrics(len(types.EncodedNoDataValue), len(oldRawValue))
 			store.Set(encodedKey, types.EncodedNoDataValue)
 		}
 	} else {
 		// Update the value.
 		newRawValue := bytes.Join([][]byte{types.EncodedDataPrefix, []byte(entry.StringValue())}, []byte{})
-		sizeDelta := float32(len(newRawValue) - len(oldRawValue))
-		ReportStoreSizeMetrics(k, sizeDelta)
+		k.reportStoreSizeMetrics(len(newRawValue), len(oldRawValue))
 		store.Set(encodedKey, newRawValue)
 	}
 
@@ -419,8 +421,7 @@ func (k Keeper) SetStorage(ctx sdk.Context, entry agoric.KVEntry) {
 				break
 			}
 			encodedAncestor := types.PathToEncodedKey(ancestor)
-			sizeDelta := float32(-len(encodedAncestor) - len(types.EncodedNoDataValue))
-			ReportStoreSizeMetrics(k, sizeDelta)
+			k.reportStoreSizeMetrics(0, len(encodedAncestor) + len(types.EncodedNoDataValue))
 			store.Delete(encodedAncestor)
 		}
 	} else {
@@ -432,8 +433,7 @@ func (k Keeper) SetStorage(ctx sdk.Context, entry agoric.KVEntry) {
 				break
 			}
 			encodedAncestor := types.PathToEncodedKey(ancestor)
-			sizeDelta := float32(len(encodedAncestor) + len(types.EncodedNoDataValue))
-			ReportStoreSizeMetrics(k, sizeDelta)
+			k.reportStoreSizeMetrics(len(encodedAncestor) + len(types.EncodedNoDataValue), 0)
 			store.Set(encodedAncestor, types.EncodedNoDataValue)
 		}
 	}