ci: enable VNC over ssh (#26106)

This PR makes it easier to SSH into CircleCI and use VNC.

See the new instructions here:

https://github.com/MetaMask/metamask-extension/blob/circleci-vnc/docs/ssh-to-circleci.md

(This code and procedure were based on the documentation from CircleCI,
which does **not** work as written
https://circleci.com/docs/browser-testing/#interacting-with-the-browser-over-vnc)

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Co-authored-by: Charly Chevalier <[email protected]>
Co-authored-by: Harika Jetpoluru <[email protected]>
Co-authored-by: seaona <[email protected]>