Adopt split repo: _python-bigquery-magics_ #14911
Description
Migrate the split-repo https://github.com/googleapis/python-bigquery-magics to https://github.com/googleapis/google-cloud-python.
The migration readiness criteria are the following, which we track via GitHub labels on this issue. These criteria apply to the split repo we are migrating from:
No open issues
No open PRs
No handwritten samples