Fixed instructor dashboard tooltip far away issue.

Ticket: [TNL-558] (https://openedx.atlassian.net/browse/TNL-558)

On Membership page of Instructor Dashboard, tooltips appear far away from the associated controls.

Sandbox Link For Testing: [Instructor Dashboard Membership Page] (http://waheedahmed.m.sandbox.edx.org/courses/edX/DemoX/Demo_Course/instructor#view-membership)