Related to:

- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3409
- https://github.com/t2bot/matrix-media-repo/releases/tag/v1.3.5
- https://github.com/matrix-org/matrix-spec-proposals/pull/3916

Support for authenticated media routes is enabled by default, but
variables are in place to disable it if necessary.

This change has not been tested.