Related to 0241c71a4c

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3270#issuecomment-2143782962

With this change, it should be possible for people to adjust the Docker
dependency from `docker.service` to something else (e.g. `pkg-ContainerManager-dockerd.service`),
or to completely eliminate it by setting `devture_systemd_docker_base_docker_service_name` to an empty string.

This makes it easier for people to use the playbook against a Synology DSM server.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3333

This is a break in backward-compatibility for people disabling
`index.html` creation via the playbook but are managing their static
website files in another way (AUX role, etc).