[AIRFLOW-533] Delegate setting autocommit in insert_rows to set_autocommit

[thyming]

Dear Airflow Maintainers,

Please accept this PR that addresses the following issues:

• https://issues.apache.org/jira/browse/AIRFLOW-533

Per Apache guidelines you need to create a Jira issue.

Testing Done:

• Unittests are required, if you do not include new unit tests please
  specify why you think this is not required. We like to improve our
  coverage so a non existing test is even a better reason to include one.

Reminders for contributors (REQUIRED!):

• Your PR's title must reference an issue on
  Airflow's JIRA.
  For example, a PR called "[AIRFLOW-1] My Amazing PR" would close JIRA
  issue Improving the search functionality in the graph view #1. Please open a new issue if required!
• Please squash your commits when possible and follow the How to write a good git commit message.
  Summarized as follows:
  1. Separate subject from body with a blank line
  2. Limit the subject line to 50 characters
  3. Do not end the subject line with a period
  4. Use the imperative mood in the subject line (add, not adding)
  5. Wrap the body at 72 characters
  6. Use the body to explain what and why vs. how

[r39132]

+1