Merge the Complement testing Docker images into a single, multi-purpose image. (#12881)

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

docker/conf-workers/shared.yaml.j2

@@ -3,8 +3,10 @@
 # configure_workers_and_start.py uses and amends to this file depending on the workers
 # that have been selected.
 
+{% if enable_redis %}
 redis:
     enabled: true
+{% endif %}
 
 {% if appservice_registrations is not none %}
 ## Application Services ##

docker/conf-workers/supervisord.conf.j2

@@ -28,6 +28,9 @@ stderr_logfile_maxbytes=0
 username=redis
 autorestart=true
 
+# Redis can be disabled if the image is being used without workers
+autostart={{ enable_redis }}
+
 [program:synapse_main]
 command=/usr/local/bin/prefix-log /usr/local/bin/python -m synapse.app.homeserver --config-path="{{ main_config_path }}" --config-path=/conf/workers/shared.yaml
 priority=10
@@ -41,4 +44,4 @@ autorestart=unexpected
 exitcodes=0
 
 # Additional process blocks
-{{ worker_config }}
+{{ worker_config }}