fix: make sure to use uniform drive count calculation (#10208)

It is possible in situations when server was deployed
in asymmetric configuration in the past such as

```
minio server ~/fs{1...4}/disk{1...5}
```

Results in setDriveCount of 10 in older releases
but with fairly recent releases we have moved to
having server affinity which means that a set drive
count ascertained from above config will be now '4'

While the object layer make sure that we honor
`format.json` the storageClass configuration however
was by mistake was using the global value obtained
by heuristics. Which leads to prematurely using
lower parity without being requested by the an
administrator.

This PR fixes this behavior.

cmd/endpoint-ellipses.go

@@ -329,28 +329,28 @@ var (
 // CreateServerEndpoints - validates and creates new endpoints from input args, supports
 // both ellipses and without ellipses transparently.
 func createServerEndpoints(serverAddr string, args ...string) (
-	endpointZones EndpointZones, setDriveCount int,
-	setupType SetupType, err error) {
+	endpointZones EndpointZones, setupType SetupType, err error) {
 
 	if len(args) == 0 {
-		return nil, -1, -1, errInvalidArgument
+		return nil, -1, errInvalidArgument
 	}
 
+	var setDriveCount int
 	if v := env.Get(EnvErasureSetDriveCount, ""); v != "" {
 		setDriveCount, err = strconv.Atoi(v)
 		if err != nil {
-			return nil, -1, -1, config.ErrInvalidErasureSetSize(err)
+			return nil, -1, config.ErrInvalidErasureSetSize(err)
 		}
 	}
 
 	if !ellipses.HasEllipses(args...) {
 		setArgs, err := GetAllSets(uint64(setDriveCount), args...)
 		if err != nil {
-			return nil, -1, -1, err
+			return nil, -1, err
 		}
 		endpointList, newSetupType, err := CreateEndpoints(serverAddr, false, setArgs...)
 		if err != nil {
-			return nil, -1, -1, err
+			return nil, -1, err
 		}
 		endpointZones = append(endpointZones, ZoneEndpoints{
 			SetCount:     len(setArgs),
@@ -358,7 +358,7 @@ func createServerEndpoints(serverAddr string, args ...string) (
 			Endpoints:    endpointList,
 		})
 		setupType = newSetupType
-		return endpointZones, len(setArgs[0]), setupType, nil
+		return endpointZones, setupType, nil
 	}
 
 	var prevSetupType SetupType
@@ -366,25 +366,25 @@ func createServerEndpoints(serverAddr string, args ...string) (
 	for _, arg := range args {
 		setArgs, err := GetAllSets(uint64(setDriveCount), arg)
 		if err != nil {
-			return nil, -1, -1, err
+			return nil, -1, err
 		}
 		var endpointList Endpoints
 		endpointList, setupType, err = CreateEndpoints(serverAddr, foundPrevLocal, setArgs...)
 		if err != nil {
-			return nil, -1, -1, err
+			return nil, -1, err
 		}
 		if setDriveCount != 0 && setDriveCount != len(setArgs[0]) {
-			return nil, -1, -1, fmt.Errorf("All zones should have same drive per set ratio - expected %d, got %d", setDriveCount, len(setArgs[0]))
+			return nil, -1, fmt.Errorf("All zones should have same drive per set ratio - expected %d, got %d", setDriveCount, len(setArgs[0]))
 		}
 		if prevSetupType != UnknownSetupType && prevSetupType != setupType {
-			return nil, -1, -1, fmt.Errorf("All zones should be of the same setup-type to maintain the original SLA expectations - expected %s, got %s", prevSetupType, setupType)
+			return nil, -1, fmt.Errorf("All zones should be of the same setup-type to maintain the original SLA expectations - expected %s, got %s", prevSetupType, setupType)
 		}
 		if err = endpointZones.Add(ZoneEndpoints{
 			SetCount:     len(setArgs),
 			DrivesPerSet: len(setArgs[0]),
 			Endpoints:    endpointList,
 		}); err != nil {
-			return nil, -1, -1, err
+			return nil, -1, err
 		}
 		foundPrevLocal = endpointList.atleastOneEndpointLocal()
 		if setDriveCount == 0 {
@@ -393,5 +393,5 @@ func createServerEndpoints(serverAddr string, args ...string) (
 		prevSetupType = setupType
 	}
 
-	return endpointZones, setDriveCount, setupType, nil
+	return endpointZones, setupType, nil
 }