🔧(docker) add missing frontent env

The env MEDIA_URL was missing in the frontend
Dockerfile. It is not necessary in our
running environment (staging / preprod ...) but it
is necessary if we want to run the frontend with
a different media url.
SW_DEACTIVATED was missing as well, we need to
deactivate the service worker in the frontend when
we test with Playwright.

src/frontend/apps/impress/.env

@@ -1,4 +1,5 @@
 NEXT_PUBLIC_API_ORIGIN=
 NEXT_PUBLIC_Y_PROVIDER_URL=
 NEXT_PUBLIC_MEDIA_URL=
-NEXT_PUBLIC_THEME=dsfr
+NEXT_PUBLIC_THEME=dsfr
+NEXT_PUBLIC_SW_DEACTIVATED=