fix: check if context is nil when logging coordination delete errors

[kylecarbs]

I'm not exactly sure how to handle this idiomatically...

See: https://github.com/coder/coder/actions/runs/8976564938/job/24653672411

[kylecarbs]

@spikecurtis we could check directly for the sql: database is closed error, but I'm weary to do so as the error isn't exported in the stdlib sql package.

[spikecurtis]

Really, we shouldn't even be starting a PGCoordinator to test the licensing APIs of Coderd. This is a canonical example of a test that is doing way to much and so errors in an unrelated part of the code are causing it to flake.

That said, PGCoordinator doesn't have a synchronous Close(). It just cancels the context. Considering that it does this cleanup work like deleting the row from the database, we really should fix the close to be synchronous. In a real deployment we would have failed to delete the row and left a bunch of cruft in the database for other Coordinators to have to filter out. So, this is a real product bug, not just a test bug.