Modal error displayed when the posting threshold in forum is exceeded

Covered by behat.   For manual testing: Prerequisites: Create a course and enroll a teacher and 2 students as: student1, student2 Create a forum activity as a teacher. Update the settings of the forum activity by going to "Settings" -> "Post threshold for blocking". Update "Time period for blocking" to "1 day" Update "Post threshold for blocking" to "3" Update "Post threshold for warning" to "2" Steps: Login as student1 and go to the forum activity created. Add a discussion post by clicking "Add discussion topic" button in the view page. Similarly add 2 more discussion post as did in step 2. Now student1 should not be able to see 'Add discussion topic' button. Click on any of the post created. The student1 should not see the 'Reply' link in those post. When logged in as student2 the 'Add discussion topic' button should be seen . Steps to verify the subscribe button (Note: this is for master branch only) Login as a teacher go to the above forum. Now check the "Subscribe to forum" button. The div element inside which this button is found should have class " navitem ml-sm-auto ".