chore(deps): upgrade keycloak to v25

[corneliusroemer]

relates to #1221

preview URL: https://test-kc25.loculus.org

Summary

Keycloak 25 works, expect for our custom terms checkbox which doesn't show with our keycloakify theme anymore so we do need to do the keycloakify work. But this is the keycloak part of the task.

This can be bumped to 26, see #3266 without requiring any changes on the keycloak side

Screenshot

PR Checklist

• All necessary documentation has been adapted.
• The implemented feature is covered by an appropriate test.

[fhennig]

Hey! I had most of these changes locally as well, worked on it yesterday. Everything except for the health endpoint, it was really a mystery to me, good find!

The commandline flags can also be passed as env vars, actually all flags can also be env vars, see docs here.