Fix prometheus metrics error on docker build

Dockerfile

@@ -120,9 +120,6 @@ FROM app-base AS release
 COPY --from=assets /app/static_final /app/static_final
 RUN honcho run --env docker/envfiles/prod.env docker/bin/build_staticfiles.sh
 
-# prometheus metrics aggregation for multiple processes
-ENV prometheus_multiproc_dir=/app/prometheus_metrics
-
 # build args
 ARG GIT_SHA=latest
 ARG BRANCH_NAME=master
@@ -134,6 +131,9 @@ RUN bin/run-sync-all.sh
 
 RUN echo "${GIT_SHA}" > ./root_files/revision.txt
 
+# prometheus metrics aggregation for multiple processes
+ENV prometheus_multiproc_dir=/app/prometheus_metrics
+
 # Change User
 RUN chown webdev.webdev -R .
 USER webdev