MQE-2462 : Updated the password to credentials file

Author: Manjusha.S

app/code/Magento/Backend/Test/Mftf/ActionGroup/AdminLoginActionGroup.xml

@@ -14,8 +14,7 @@
         </annotations>
         <arguments>
             <argument name="username" type="string" defaultValue="{{_ENV.MAGENTO_ADMIN_USERNAME}}"/>
-            <argument name="password" type="string" defaultValue="{{_ENV.MAGENTO_ADMIN_PASSWORD}}"/>
-        </arguments>
+            <argument name="password" type="string" defaultValue="{{_CREDS.magento/MAGENTO_ADMIN_PASSWORD}}"/></arguments>
 
         <amOnPage url="{{AdminLoginPage.url}}" stepKey="navigateToAdmin"/>
         <fillField selector="{{AdminLoginFormSection.username}}" userInput="{{username}}" stepKey="fillUsername"/>