branch-protection-tighten: add clarification about output in dry mode

branch-protection-tighten aims to protect branches that were unprotected
during branch-protection-relax. Howerver in dry mode, branch-protection-relax
doesn't unprotect branches on purpose. Thus, branch-protection-tighten
won't report that it will protect branches because they are already
protected due to dry mode. So, we cannot check during the dry mode that
branch-protection-tighten will reprotect branches.

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

.gitlab-ci/branching.yml

@@ -156,6 +156,12 @@ branch-protection-tighten:
         sed
         gitlab-rulez/bookworm-backports # required to avoid python deprecation warnings
     - sed -i "s/$RELEASE/$NEXT_RELEASE/g" gitlab-rulez/rulez.yaml
+  after_script:
+    - |
+      if [ "$NOACT" == 1 ]
+      then
+        echo "👷 gitlab-rulez is running in dry mode, thus it only reports changing the default branch and not protecting branches"
+      fi
   rules:
     - if: $CI_JOB_NAME =~ $FORCE_JOB_RUN
       when: manual