R1:ee2e85a0bb8d

Fix several migration issues with the Task/Counter patch

Summary:
People hit three issues with D3914:

- As per T2059, we applied a schema change from a `.php` patch, which currently does not work if you use a different user to make schema changes than for normal use.
- Since the change in question is idempotent, just move it to a `.sql` patch. We'll follow up in T2059 and fix it properly.
- Rogue daemons at several installs used old code (expecting autoincrement) to insert into the new table (no…