MDL-78806 behat: More lenient checking of page title

Instead of doing an exact checking of the page title in
\behat_hooks::before_step(), do a more lenient check by checking that
the page title contains the acceptance test's site name.

lib/tests/behat/behat_hooks.php

@@ -520,7 +520,7 @@ public function before_step(BeforeStepScope $scope) {
                     'or that your web server is correctly set up and started.';
 
                 $this->find(
-                        "xpath", "//head/child::title[normalize-space(.)='" . behat_util::BEHATSITENAME . "']",
+                        "xpath", "//head/child::title[contains(., '" . behat_util::BEHATSITENAME . "')]",
                         new ExpectationException($message, $session)
                     );