Coin: use toolchain for the CI test

Build the toolchain recipe for CI test, which allows us the limit
what recipes are included.

Change-Id: I9c532dcc97979bf40a0ca094850d7a0602f2f9d0
Reviewed-by: Mikko Gronoff <mikko.gronoff@qt.io>
(cherry picked from commit d4232d5a71)

coin/module_config.yaml

@@ -138,8 +138,8 @@ instructions:
 
       echo "require ${SOURCE_DIR}/coin/test-configs.inc" >> conf/local.conf
 
-      # build all recipes found in the layer
-      bitbake $(find ${SOURCE_DIR} -name *.bb | xargs -n1 basename | sed -e 's/\([^._]*\).*/\1/')
+      # build toolchain which should include all supported recipes
+      bitbake meta-toolchain-qt6
     filename: "{{.BuildDir}}/start-build"
     fileMode: 420
   - type: ExecuteCommand