style: align plugin renaming (#10868)

config/config.go

@@ -615,10 +615,8 @@ func printFilteredInputs(inputFilters []string, commented bool) {
 	// Print Inputs
 	for _, pname := range pnames {
 		// Skip inputs that are registered twice for backward compatibility
-		if pname == "cisco_telemetry_gnmi" {
-			continue
-		}
-		if pname == "KNXListener" {
+		switch pname {
+		case "cisco_telemetry_gnmi", "io", "KNXListener":
 			continue
 		}
 		creator := inputs.Inputs[pname]
@@ -1246,14 +1244,6 @@ func (c *Config) addInput(name string, table *ast.Table) error {
 		return nil
 	}
 
-	// Legacy support renaming io input to diskio
-	if name == "io" {
-		if err := c.printUserDeprecation("inputs", name, nil); err != nil {
-			return err
-		}
-		name = "diskio"
-	}
-
 	// For inputs with parsers we need to compute the set of
 	// options that is not covered by both, the parser and the input.
 	// We achieve this by keeping a local book of missing entries

plugins/inputs/diskio/diskio.go

@@ -184,4 +184,8 @@ func init() {
 	inputs.Add("diskio", func() telegraf.Input {
 		return &DiskIO{ps: ps, SkipSerialNumber: true}
 	})
+	// Backwards compatible alias
+	inputs.Add("io", func() telegraf.Input {
+		return &DiskIO{ps: ps, SkipSerialNumber: true}
+	})
 }