CI check if schema changes were cleanly applied

Recently we've seen a case were schema changes were manually adapted
so the order was not matching the automatically generated
`db/structure.sql`.

To help people commit a clean schema file, I've introduced
`script/regenerate-schema`. This change uses that script to check if
the committed file matches the file automatically generated.

.gitlab/ci/rails.gitlab-ci.yml

@@ -143,6 +143,7 @@ db:migrate:reset:
 db:check-schema:
   extends: .db-job-base
   script:
+    - scripts/regenerate-schema
     - source scripts/schema_changed.sh
 
 db:migrate-from-v11.11.0:

scripts/schema_changed.sh

@@ -2,13 +2,13 @@
 
 schema_changed() {
   if [ ! -z "$(git diff --name-only -- db/structure.sql)" ]; then
-    printf "db/structure.sql after rake db:migrate:reset is different from one in the repository"
+    printf "Schema changes are not cleanly committed to db/structure.sql\n"
     printf "The diff is as follows:\n"
     diff=$(git diff -p --binary -- db/structure.sql)
     printf "%s" "$diff"
     exit 1
   else
-    printf "db/structure.sql after rake db:migrate:reset matches one in the repository"
+    printf "Schema changes are correctly applied to db/structure.sql\n"
   fi
 }