clean up insert_or_update_batch() method

[melange396]

• remove insert_or_update_bulk()
• roll run_dbjobs() logic into the insert_batch method
  • can get rid of "suppress_jobs" argument too, unless someone can come up with a good reason for keeping it

https://github.com/cmu-delphi/delphi-epidata/blob/dev/src/acquisition/covidcast/database.py#L159

[dshemetov]

If I may batch this in:

• consider handling cc_rows as a generator
• the code below splits the insert query into batches (and doubles the line-length of that function) but as far as I can understand executemany already does that batching