remove obsolete schedule js, css and templates, fixes #4840

resources/assets/javascripts/bootstrap/resources.js

resources/assets/javascripts/init.js

resources/assets/javascripts/lib/instschedule.js

resources/assets/javascripts/lib/schedule.js

resources/assets/stylesheets/highcontrast.scss

resources/assets/stylesheets/print.scss

resources/assets/stylesheets/scss/schedule.scss

resources/assets/stylesheets/scss/tables.scss

resources/assets/stylesheets/studip.scss

templates/calendar/calendar_view.php

templates/calendar/entries/empty_entry.php

templates/calendar/entries/entry.php

templates/calendar/entries/grouped_entry.php

templates/calendar/entries/icons.php