Chore: Remove unused Go code (#28852)

* Chore: Remove more unused Go code

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/api/datasource/validation.go

@@ -24,7 +24,9 @@ func (e URLValidationError) Error() string {
 	return fmt.Sprintf("validation of data source URL %q failed: %s", e.URL, e.Err.Error())
 }
 
+// nolint:unused
 // Unwrap returns the wrapped error.
+// Used by errors package.
 func (e URLValidationError) Unwrap() error {
 	return e.Err
 }