MAINT: try switching the cosmodc2 notebook to use async TAP

[bsipocz]

The cosmodc2 TAP notebook is frequently runs into timeout errors when run in CI (see e.g. https://github.com/Caltech-IPAC/irsa-tutorials/actions/runs/13363252210 where it timeouted 3 out of the 5 jobs. But sometimes it passes all 5).
The example is using service.search which defaults to run_sync.

I wonder if this is a good point to showcase async TAP queries, and if that would resolve the timeouts? (The latter cannot really be directly tested as it's not exactly deterministic when to fail)

cc @vandesai1 as the author of the notebook.