As an external contributor, I want preview builds to be generated for my pull requests, so that we can preview the changes publicly and discuss collaboratively.

[eddybrando]

Currently, external contributors' PRs don't generate preview builds. This is due to the images requiring access to secrets to fetch necessary Airtable data.

But lately we've implemented mock data for local development so that one doesn't need to fetch the Airtable data to preview one's changes.

We can use this approach as well for external contributor preview builds and leverage the mock data.

### Tasks
- [ ] https://github.com/Qiskit/qiskit.org/issues/3505

[eddybrando]

This might also close #1963

[jackoconnordev]

I think this would be useful (for what that's worth 😛)