MDL-45699 behat: Don't use behat/lib.php functions in core.

behat/lib.php script should not be usually included, neither any of its functions
used within mooodle code at all. It's for exclusive use of behat and
moodle setup.php. For places requiring a different/special behavior
needing to check if are being run  as part of behat tests, use:
    if (defined('BEHAT_SITE_RUNNING')) { ...

cache/classes/factory.php

@@ -126,7 +126,7 @@ public static function instance($forcereload = false) {
                 // situation. It will use disabled alternatives where available.
                 require_once($CFG->dirroot.'/cache/disabledlib.php');
                 self::$instance = new cache_factory_disabled();
-            } else if ((defined('PHPUNIT_TEST') && PHPUNIT_TEST) || behat_is_test_site()) {
+            } else if ((defined('PHPUNIT_TEST') && PHPUNIT_TEST) || defined('BEHAT_SITE_RUNNING')) {
                 // We're using the test factory.
                 require_once($CFG->dirroot.'/cache/tests/fixtures/lib.php');
                 self::$instance = new cache_phpunit_factory();
@@ -336,7 +336,7 @@ public function create_config_instance($writer = false) {
         // The class to use.
         $class = 'cache_config';
         // Are we running tests of some form?
-        $testing = (defined('PHPUNIT_TEST') && PHPUNIT_TEST) || behat_is_test_site();
+        $testing = (defined('PHPUNIT_TEST') && PHPUNIT_TEST) || defined('BEHAT_SITE_RUNNING');
 
         // Check if this is a PHPUnit test and redirect to the phpunit config classes if it is.
         if ($testing) {

lib/behat/lib.php

@@ -17,7 +17,13 @@
 /**
  * Behat basic functions
  *
- * It does not include MOODLE_INTERNAL because is part of the bootstrap
+ * It does not include MOODLE_INTERNAL because is part of the bootstrap.
+ *
+ * This script should not be usually included, neither any of its functions
+ * used, within mooodle code at all. It's for exclusive use of behat and
+ * moodle setup.php. For places requiring a different/special behavior
+ * needing to check if are being run as part of behat tests, use:
+ *     if (defined('BEHAT_SITE_RUNNING')) { ...
  *
  * @package    core
  * @category   test