fix appointment remove student link
fix appointment remove student link

fixes CNVS-35839

test plan:
- Create a teacher, student, course and appointment group
- Have the student sign up for an appointment slot
- Have the teacher click on the slot, the modal appears
- Navigate to the button to remove the student from the slot
- Not that screenreader reads "Remove Attendee X" where X is the
  attendee name

Change-Id: Ibf3768f141c575ae8577d918615294bd0e88d2dc
Reviewed-on: https://gerrit.instructure.com/106179
Tested-by: Jenkins
Reviewed-by: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>
QA-Review: Heath Hales <8ca81b68c7e2592ac614bd07f22fcc735ca55f93@instructure.com>
Product-Review: Dan Sasaki

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms