libbeat/cfgfile: remove futile errors.Is call (#40851)

Also remove the no-lint directive and use errors.As to identify the type of
the error returned by createRunner.

libbeat/cfgfile/list.go

@@ -131,8 +131,7 @@ func (r *RunnerList) Reload(configs []*reload.ConfigWithMeta) error {
 	for hash, config := range startList {
 		runner, err := createRunner(r.factory, r.pipeline, config)
 		if err != nil {
-			errors.Is(err, &common.ErrInputNotFinished{})
-			if _, ok := err.(*common.ErrInputNotFinished); ok { //nolint:errorlint // ErrInputNotFinished is a struct type, not an expression/error value
+			if errors.As(err, new(*common.ErrInputNotFinished)) {
 				// error is related to state, we should not log at error level
 				r.logger.Debugf("Error creating runner from config: %s", err)
 			} else {