fullcalendar: changed loading indicator size to 32x32 px, fixes #3626

Closes #3626

Merge request studip/studip!2618

resources/assets/javascripts/lib/fullcalendar.js

@@ -604,8 +604,8 @@ class Fullcalendar
                             $('<div id="loading-spinner" style="position: absolute; top: calc(50% - 55px); left: calc(50% + 135px); z-index: 9001;">').html(
                                 $('<img>').attr('src', STUDIP.ASSETS_URL + 'images/loading-indicator.svg')
                                     .css({
-                                        width: 64,
-                                        height: 64
+                                        width: 32,
+                                        height: 32
                                     })
                             )
                         );