fix(storybook): return 404 for unsupported API versions in baseMocks

[kunaldevsahu]

Summary

This PR updates Storybook baseMocks to return a 404 HTTP response
for unsupported API versions instead of throwing a generic network error.
This aligns mock behavior with actual backend responses and improves
error handling consistency.

Related Issue

Fixes #4735

Changes

• Updated baseMocks to return HTTP 404 for unsupported API versions
• Replaced generic network error handling logic

Steps to Test

1. Run Storybook locally
2. Trigger a request using an unsupported API version
3. Verify that the response returns a 404 status instead of a network error

Screenshots (if applicable)

N/A

Notes for the Reviewer

• This change only affects Storybook mock behavior.
• No backend logic was modified.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: kunaldevsahu / name: kunaldevsahu (e10105d)

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[gambtho]

I think the linked issue #4735 describes a problem with apiextensions.k8s.io/v1beta1/customresourcedefinitions endpoints using HttpResponse.error() to simulate network failures instead of returning 404. However, this PR changes the wsMultiplexer endpoint instead. The wsMultiplexer HTTP mock exists intentionally to suppress MSW "unhandled request" warnings for WebSocket URLs — HttpResponse.error() is the correct behavior there since MSW cannot intercept WebSocket upgrade connections via http.get() handlers.

[skoeva]

want to echo the last comment, this PR isn't addressing the root issue

[k8s-ci-robot]

PR needs rebase.

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