Investigate schema validation errors for dev stuff

[theosanderson]

We just turned off schema validation for dev workflows: #3685 which I think largely makes sense, for the reasons discussed in the issue, but...

at the same time we realised that the adding of the schema made various dev things fail on main, which was unexpected. We should probably make sure everything on main does obey the schema, even if it's CI stuff.

Failures:
https://github.com/loculus-project/loculus/actions/runs/13308090063/job/37163614481
https://github.com/loculus-project/loculus/actions/runs/13308090052/job/37163617397 (same issue)
https://github.com/loculus-project/loculus/actions/runs/13308090087/job/37163615901 (testconfig)

We could consider specifically running with schema checks for CI runs on main (but that may be unnecessarily complex)

[theosanderson]

This is where testConfig is used

loculus/kubernetes/loculus/templates/loculus-preprocessing-deployment.yaml

Line 7 in 317aae4

{{- $keycloakHost := $testconfig | ternary "http://localhost:8083" "http://loculus-keycloak-service:8083" }}

we may be able to refactor this now to be done differnetly