Logging to BigQuery can fail if number of rows to insert is too large

[fdmalone]

Pulled from #2989. I ran into an issue where load_bq.py would fail as the number of rows was too large for insert_rows. My workaround was to batch over slices of the jobs list with a batch size set to 10000 (which I think is the upper limit for insert_rows).

I can send a PR with the patch but I was a bit hesitant given the lack of unit tests for the script and adding those would be a bit of work (faking the client etc)

[mr0re1]

@fdmalone , your contribution would be very welcome, with or without tests.

[cdunbar13]

Checking in to see if you've had a chance to submit a PR for this.

[fdmalone]

I haven't, I'll try to get to it shortly

[tpdownes]

Marking this issue as "fixed, not released" because it is on our develop branch. It should be in the next release, which will probably be numbered v1.41.0.