chore: replace jest with vitest in backend project #4642

Job	Run time
Builds (backend)	2m 14s
Builds (frontend)	11s
Builds (migrations)	14s
Deploys / Database / Helm (Crunchy)	3m 21s
Deploys / Helm (stack)	1m 26s
Tests / Load (backend)	36s
Tests / E2E (chromium)	1m 11s
Tests / Load (frontend)	35s
Tests / Integration	13s
Tests / E2E (Google Chrome)	1m 51s
Tests / E2E (firefox)	1m 10s
Tests / E2E (safari)	1m 32s
Tests / E2E (Microsoft Edge)	1m 55s
PR Results	1s
	16m 30s

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