[task_manager_refactor] Submit job to dispatcher as part of transaction

[AlanCoding]

SUMMARY

This is incomplete, because it creates a UX problem with the websockets. This was expected.

The UI status obtains the "waiting" status while the job is supposed to be shown as "running".

The crux of this PR is that we really need to make this change because a very large fraction of the time the task manager runs is spent in the on_commit method. The two unresolved issues are:

• [ ] the "waiting" websocket status message, leading to the bug in the screenshot
• [ ] the need to do git webhook requests... which I think can be moved in the same way create_partition is here.

ISSUE TYPE

• Bug or Docs Fix

COMPONENT NAME

• API