Performance: Split large dependencies into their own individual chunks (take 2)

Created by: umpox

Note: This was previously merged through https://github.com/sourcegraph/sourcegraph/pull/26360. It caused a bug, so I reverted it and have done some additional work to avoid this bug happening again.

I am more confident in this PR as:

1. The actual bug is fixed, by the addition of this line to our HTML file: https://github.com/sourcegraph/sourcegraph/blob/c24ed7ce6799b728232d4cdb7bf1036626b7378d/cmd/frontend/internal/app/ui/app.html#L67
2. I've updated our standalone server to make adding these new files explicit. Retracing my steps with these changes showed that this would have caught the original bug. https://github.com/sourcegraph/sourcegraph/pull/26649
3. Our QA tests now run on the main pipeline and will block production deploys. So if our standalone server still doesn't match production well, these tests should hopefully catch it again and we won't actually deploy the bug