MDL-70167 behat: Rewrite attribute check steps

This commit updates the following steps to use the
`the_attribute_of_should_be_set` step under the hood:
- the [element] [type] should be disabled
- the [element] [type] should be enabled
- the [element] [type] should be readonly
- the [element] [type] should not be readonly

This reduces unnecssary code duplication.

lib/tests/behat/behat_general.php

@@ -921,13 +921,7 @@ protected function check_element_order(
      * @param string $selectortype The type of element where we are looking in.
      */
     public function the_element_should_be_disabled($element, $selectortype) {
-
-        // Transforming from steps definitions selector/locator format to Mink format and getting the NodeElement.
-        $node = $this->get_selected_node($selectortype, $element);
-
-        if (!$node->hasAttribute('disabled')) {
-            throw new ExpectationException('The element "' . $element . '" is not disabled', $this->getSession());
-        }
+        $this->the_attribute_of_should_be_set("disabled", $element, $selectortype, false);
     }
 
     /**
@@ -939,13 +933,7 @@ public function the_element_should_be_disabled($element, $selectortype) {
      * @param string $selectortype The type of where we look
      */
     public function the_element_should_be_enabled($element, $selectortype) {
-
-        // Transforming from steps definitions selector/locator format to mink format and getting the NodeElement.
-        $node = $this->get_selected_node($selectortype, $element);
-
-        if ($node->hasAttribute('disabled')) {
-            throw new ExpectationException('The element "' . $element . '" is not enabled', $this->getSession());
-        }
+        $this->the_attribute_of_should_be_set("disabled", $element, $selectortype, true);
     }
 
     /**
@@ -957,12 +945,7 @@ public function the_element_should_be_enabled($element, $selectortype) {
      * @param string $selectortype The type of element where we are looking in.
      */
     public function the_element_should_be_readonly($element, $selectortype) {
-        // Transforming from steps definitions selector/locator format to Mink format and getting the NodeElement.
-        $node = $this->get_selected_node($selectortype, $element);
-
-        if (!$node->hasAttribute('readonly')) {
-            throw new ExpectationException('The element "' . $element . '" is not readonly', $this->getSession());
-        }
+        $this->the_attribute_of_should_be_set("readonly", $element, $selectortype, false);
     }
 
     /**
@@ -974,12 +957,7 @@ public function the_element_should_be_readonly($element, $selectortype) {
      * @param string $selectortype The type of element where we are looking in.
      */
     public function the_element_should_not_be_readonly($element, $selectortype) {
-        // Transforming from steps definitions selector/locator format to Mink format and getting the NodeElement.
-        $node = $this->get_selected_node($selectortype, $element);
-
-        if ($node->hasAttribute('readonly')) {
-            throw new ExpectationException('The element "' . $element . '" is readonly', $this->getSession());
-        }
+        $this->the_attribute_of_should_be_set("readonly", $element, $selectortype, true);
     }
 
     /**