remove tooltip from date header on syllabus page

assignments' individual due dates still have a tooltip that
shows the full date and time for both the course and local
time zones, but the header on the left just shows the date,
and adding a tooltip with a midnight time adds no new information
(just confusion).

fixes CNVS-15413

Change-Id: Ice08d89ecfddf22d558abb389e7ecc94465c434d
Reviewed-on: https://gerrit.instructure.com/46623
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>

Author: jstanley0

app/views/jst/courses/Syllabus.handlebars

@@ -21,7 +21,7 @@
   <tbody>
     {{#each dates}}
     <tr class="date{{#if passed}} date_passed{{/if}}{{#if date}} events_{{strftime date "%Y_%m_%d"}}{{/if}}">
-      <th scope="row" class="day_date" data-date="{{#if date}}{{strftime date "%Y_%m_%d"}}{{/if}}" {{ contextSensitiveDatetimeTitle date }}>
+      <th scope="row" class="day_date" data-date="{{#if date}}{{strftime date "%Y_%m_%d"}}{{/if}}">
         {{#if date}}
           {{tDateToString date "medium_with_weekday"}}
         {{/if}}