Deletes the trusted-registry entry for one hostname.

Call this on the Runtime service path https://<JPD_HOST>/runtime/api/v1/trusted_registries/{registryUrl}. registryUrl is the hostname exactly as stored, and the lookup is case-sensitive.

Requires a Runtime Manager, which is a platform admin or a Project Admin on the default project. Other callers receive 403.

A 200 response is returned even when no entry matched the hostname. After deletion, images from that host are marked Untrusted registry the next time Runtime rechecks them, at most every 5 minutes by default.