Use snapshot_platform helper in SFR Box tests (home-assistant#157481)

Author: epenet

homeassistant/components/sfr_box/quality_scale.yaml

@@ -38,9 +38,6 @@ rules:
     status: todo
     comment: |
       - 93% on diagnostics / 92% on sensors, need to improve overall coverage
-      - It would be nice to use the snapshot helper as currently it would just throw everything in a list
-      - We also test the devices in each platform, kinda overkill
-      - We should use entity_registry_enabled_by_default instead to enable entities
   integration-owner: done
   docs-installation-parameters:
     status: todo