[AMP][backcompat] Remove AssetDaemonCursor backcompat logic

[OwenKephart]

Summary & Motivation

This logic was only necessary for the first tick after a user upgraded from dagster version <1.6.0 to >=1.6.0.

Even then, its only purpose was to improve the performance of the first tick after that upgrade. Given the fact that it is possible for it to hit errors in this code path, our time partitions definition has changed serialization version (invalidating basically all stored data a user would have anyway), and it's not really critical to any use cases, the best option is to just remove it entirely.

How I Tested These Changes