docker: always merge .yaml.local in conf_get() (#2272)

With this change, all queries to the configuration will return the
values from .local if they are set. However, conf_set will only write
to .yaml and never to .local. This means users can potentially override
values that are supposed to be under control of the entrypoint
(credentials and things set from envvars).

docker/docker_start.sh

@@ -56,7 +56,7 @@ conf_get() {
     if [ $# -ge 2 ]; then
         yq e "$1" "$2"
     else
-        yq e "$1" "$CONFIG_FILE"
+        cscli config show-yaml | yq e "$1"
     fi
 }