feat(bigquery): add support for custom QueryJobConfig in BigQuery.cursor.execute method

[TobKed]

My change allows to support use_legacy_sql.

[plamut]

Thanks for this!

Before merging, though, we would still need to add the new parameter description to the method's docstring, and cover the change in the tests. We would be happy to provide any assistance, should that be necessary.

[TobKed]

Thanks for feedback @plamut . I've applied changes suggested by you however still waiting for Kokoro check.

[TobKed]

Kokoro - Recommender check has failed however logs are empty. @plamut do you know maybe why it failed? I have no clue what is the reason.

[plamut]

@TobKed Seems like flakiness, saw the same on a few other PRs as well. I will try restarting the jobs.

Update: Actually, it seems to be a real issue in the Recommender library, not just flakiness. It currently happens on all PRs, and it's not related to the changes made here.

[plamut]

LGTM, a custom job config indeed changes the SQL mode for the job on the backend.

[TobKed]

@plamut thanks for feedback! Good luck with fixing Kokoro :)

[tswast]

LGTM. I'm a bit concerned about deviating from the DB-API spec for execute(), but I see we already deviate due to job_id.