ci: Merge 'source_check' stage into 'review'

GNOME apps use 'review' for the CI stage that generates and exports a
flatpak bundle after a successful build, so they need some other name
for anything that is checked before building; that's how we ended up
with the somewhat awkward 'source_check' stage (inherited from Polari).

But since the commit log check added a 'review' stage that runs pre-build,
use that for all checks that are performed before the build stage.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/627

.gitlab-ci.yml

@@ -1,6 +1,5 @@
 stages:
  - review
- - source_check
  - build
  - test
 
@@ -26,7 +25,7 @@ check_commit_log:
 
 js_check:
     image: registry.gitlab.gnome.org/gnome/gnome-shell/extension-ci:v1
-    stage: source_check
+    stage: review
     script:
         - find js -name '*.js' -exec js60 -c -s '{}' ';' 2>&1 | tee $JS_LOG
         - (! grep -q . $JS_LOG)