Revert "AuthManager: Commit transaction after auto-creating a user"

Revert "AuthManager: Commit transaction after auto-creating a user"

* 81be9512a022 should obviate the main desire for this.
  The normal commit step is now relied upon again.
* 820f5d6ce57f and a26fbb67054 enforce DBO_TRX transactions.
* Committing the implicit transaction(s) prematurely is bad
  for web request and cross-DB transactionality. Only code
  that has clear outermost DB context (e.g. jobs/maintenance)
  should be doing things like this as it becomes hard to reason
  about (e.g. how much the request/caller needs atomicity
  or whether there is an outer (start|end)Atomic section).

This reverts commit 83c66caa0831086db7c2033ddda38106584060d0.

Change-Id: I1a5533b239e53f2089f239651c6fdf97e51c9062