Adjust default behavior of "migrate" command (#12320)

* Adjust default behavior of "migrate" command

- Does not create new migration files automatically

* Add dummy field - ensure detected by CI

* Revert "Add dummy field - ensure detected by CI"

This reverts commit e7a101fe87.

* Fix typo

* Adjust contributing docs

* Add CHANGELOG entry

.github/workflows/check_translations.yaml

@@ -46,4 +46,6 @@ jobs:
         run: |
           python ./.github/scripts/check_source_strings.py --frontend --backend
       - name: Check Migration Files
-        run: python3 .github/scripts/check_migration_files.py
+        run: |
+          invoke migrate --detect
+          python3 .github/scripts/check_migration_files.py

.github/workflows/qc_checks.yaml

@@ -405,7 +405,9 @@ jobs:
       - name: Test Translations
         run: invoke dev.translate
       - name: Check Migration Files
-        run: python3 .github/scripts/check_migration_files.py
+        run: |
+          invoke migrate --detect
+          python3 .github/scripts/check_migration_files.py
       - name: Coverage Tests
         run: invoke dev.test --check --coverage --translations
       - name: Upload raw coverage to artifacts