fix: Remove non-existing connector mention from SQLAlchemy doc

[ptiurin]

Description

We don't have Redash connector in Firebolt 2.0, we should remove mention of it to avoid confusing the customers.

When should this PR be released to the public?

immediate release

Documentation Checklist

• I've previewed my documentation locally running make start-local (or using this tutorial)
• I've validated that indexing works and that I'm able to navigate to the documentation page from the table of contents

If this PR touches a function implementation (aggregate, scalar, or table-valued):

• I've made sure my documentation is aligned with these guidelines on function documentation
• I've validated that the parent of my docs page is set correctly and the function shows up in the right category of the table of contents
• I've made sure that the function was added to the function glossary

[nanimal-fb]

The PR check on this repo isn't working. I'll look into it when Arushi gets back. I had to go a roundabout way to merge. Closing this PR but your requested change is live. Please submit all future PRs only to the staging repo.