Performance: Streamline `blob.bundle.js` (Blob related entrypoints)

[umpox]

Description

Goal: Reduce code required to be downloaded before blob pages can be shown.

Reason:

• Required before we can render blobs (and other pages) in the Sourcegraph application.
• Part of the core workflow, but isn't necessarily going to be significantly affected by any UX changes here. Would be great if we could get this streamlined and enforce a smaller size before making those changes too.

A/C

• Lower blob related bundle size
• Update our bundlesize config to enforce this and ensure we don't regress in future.

[sourcegraph-bot-2]

Heads up @taylorsperry @jasongornall - the "team/frontend-platform" label was applied to this issue.

[umpox]

Note: We should ensure we finish https://github.com/sourcegraph/sourcegraph/issues/39598 first, as that will likely fix some areas where we were not bundle splitting and possibly introduce other elements into theses specific bundles.