Changed none selected to none, to be used when there are none availab… (

#19977)

* Changed none selected to none, to be used when there are none available to select and when none are selected.
Set select to be readonly is they cannot select any options

* Update plugins.php

* Update plugins.php

* Update en-GB.ini

* Update en-GB.ini

* Update plugins.php

* Update plugins.php

* Update plugins.php

* Update plugins.php

* Update plugins.php

Space/tabbing for drone.

* Update plugins.php

libraries/joomla/form/fields/plugins.php

@@ -157,4 +157,21 @@ protected function getOptions()
 
 		return array_merge($parentOptions, $options);
 	}
+
+	/**
+	 * Method to get input and also set field readonly.
+	 *
+	 * @return  string  The field input markup.
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	protected function getInput()
+	{
+		if (count($this->options) === 1 && $this->options[0]->text === JText::_('JOPTION_DO_NOT_USE'))
+		{
+			$this->readonly = true;
+		}
+
+		return parent::getInput();
+	}
 }