web: remove integrations banners (leftovers)
Created by: taras-yemets
Follow-up on https://github.com/sourcegraph/sourcegraph/pull/38715 (see this thread).
Test plan
No additional UI changes. Ensure that CI passes. Test plan isnthe same as in https://github.com/sourcegraph/sourcegraph/pull/38715.
App preview:
Check out the client app preview documentation to learn more.