Style cancel/confirm button pairs consistently

[axlewin]

Across both sites: where "cancel" and "confirm" options (or similar) appear next to each other, "cancel" should be keyline and to the left of the solid "confirm".

[codecov]

Codecov Report

❌ Patch coverage is 29.41176% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 41.64%. Comparing base (74f2490) to head (90251a6).
⚠️ Report is 47 commits behind head on main.

Files with missing lines	Patch %	Lines
...elements/modals/TeacherConnectionModalCreators.tsx	27.27%	8 Missing ⚠️
...components/elements/modals/GroupsModalCreators.tsx	50.00%	2 Missing ⚠️
...omponents/elements/modals/AccountDeletionModal.tsx	0.00%	1 Missing ⚠️
...pp/components/pages/RegistrationSetPreferences.tsx	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1823      +/-   ##
==========================================
- Coverage   41.64%   41.64%   -0.01%     
==========================================
  Files         543      543              
  Lines       23844    23843       -1     
  Branches     7910     7886      -24     
==========================================
- Hits         9931     9930       -1     
  Misses      13267    13267              
  Partials      646      646              

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