cr: improve custom replset name configuration impl

Author: gkech

pkg/psmdb/container.go

@@ -227,25 +227,19 @@ func containerArgs(ctx context.Context, cr *api.PerconaServerMongoDB, replset *a
 		args = append(args, "--auth")
 	}
 
+	replSetName := replset.Name
+	if name, err := replset.CustomReplsetName(); err == nil {
+		replSetName = name
+	}
+
 	args = append(args,
 		"--dbpath="+config.MongodContainerDataDir,
 		"--port="+strconv.Itoa(int(replset.GetPort())),
-		"--replSet="+replset.Name,
+		"--replSet="+replSetName,
 		"--storageEngine="+string(replset.Storage.Engine),
 		"--relaxPermChecks",
 	)
 
-	name, err := replset.CustomReplsetName()
-	if err == nil {
-		// given that --auth option is optional, we cannot rely on the fixed hardcoded index.
-		for i, arg := range args {
-			if len(arg) >= 9 && arg[:9] == "--replSet" {
-				args[i] = "--replSet=" + name
-				break
-			}
-		}
-	}
-
 	if *cr.Spec.TLS.AllowInvalidCertificates || cr.CompareVersion("1.16.0") < 0 {
 		args = append(args, "--sslAllowInvalidCertificates")
 	}