Replace as any mock fixtures in three app test files with shoehorn #2852

Three test files added in #2802, #2816 and #2817 build partial mock objects with } as any and an // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion above each:

These are the case @total-typescript/shoehorn is for: fromPartial({...}) gives the same brevity while still type-checking the fields you do set, so a renamed or retyped field breaks the test instead of sailing through the assertion.

Swapping them lets the ratchet baseline in scripts/ci/ratchet-baseline.json come back down (app/as-any 215 → 208, app/eslint-disable 143 → 136) via yarn ratchet:update.

Noticed while re-baselining the ratchet in #2661.