feat: Assign result in send_query_stale_warning to stabilize test

[detule]

Hi @krlmlr

Seeing ( intermittent ) failures in odbc pipelines, that I am having trouble replicating on my boxes. They are windows only + sql server specific, though I think that may be a red herring.

I think the failures may be caused by the return value of dbSendQuery in the test below not being assigned to a named variable. I wonder if because of that, it's possible for the "rvalue" result object to be garbage collected before the dbDisconnect call below. If that were to happen, there would be no warning emitted when the disconnect call goes through, as the result has already been destroyed/released.

I listed four failures pipeline above. In between failure three and four I ran an identical job using this branch of DBItest and the pipeline passed. Somewhat unscientific, I know, and without a windows box to test on this is mostly guesswork.

Strike against this theory is that I can't think of any recent changes that would have caused this issue to suddenly flare up. Then again, I always struggle with issues related to garbage collection.

Cheers.

[krlmlr]

Thanks, looks good, and I like the symmetry with the test above.

[krlmlr]

Thanks!