Remove downstream config

It is outdated and it was discussed that it would be removed in favor
of other options.

Change-Id: If2468c84d8ca8197587577ae3d72aeb96c822c5f
Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
Reviewed-by: Jukka Jokiniva <jukka.jokiniva@qt.io>

coin/module_config.yaml

@@ -4,14 +4,6 @@ accept_configuration:
   property: features
   not_contains_value: Disable
 
-downstream_check:
-  mode: build
-  modules:
-    ../qtdeclarative:
-      ref: dev
-  configurations:
-    - rhel-8.4
-
 machine_type:
   Build:
     cores: 8