Before too many more homeserver dockerfiles are written, what do people think about removing the COMPLEMENT_CA environment variable, and making its behaviour the default? /ca will just be mounted in all docker containers, and homeserverd dockerfiles can choose to use the certificate and key in /ca or not.

Existing dockerfiles, such as the Synapse Monolith one will need to be updated, but I've been planning to adjust that one to use Complement's CA anyhow.