Revert "Merge pull request #63 from Shopify/pr_lockwait_to_set"

This reverts commit 037da76406ee130ea25a38a0295481a2a33e7fdc, reversing
changes made to 8730691d133db4f278261d28c3bb041d0c1ccc61.

Conflicts:
	spec/integration/lock_wait_timeout_spec.rb

Reverting this for now as DM and AR 2.3 are failing.