Always build underlay as release

.circleci/config.yml

@@ -321,7 +321,7 @@ executors:
       <<: *common_environment
       CACHE_NONCE: "Debug"
       OVERLAY_MIXINS: "debug ccache coverage-gcc"
-      UNDERLAY_MIXINS: "debug ccache"
+      UNDERLAY_MIXINS: "release ccache"
   release_exec:
     docker:
       - image: rosplanning/navigation2:master.release

.dockerhub/debug/hooks/build

@@ -3,7 +3,7 @@ set -ex
 
 export FROM_IMAGE=osrf/ros2:nightly
 export FAIL_ON_BUILD_FAILURE=""
-export UNDERLAY_MIXINS="debug ccache"
+export UNDERLAY_MIXINS="release ccache"
 export OVERLAY_MIXINS="debug ccache coverage-gcc"
 
 docker build \