Remove time updates in AfterFind for Model and Transaction

[morremeyer]

We currently explicitly set the timestamp to UTC in the AfterFind(*gorm.DB) error methods of the Model and Transaction types.

This is done since the database saves and returns them as +00:00.

However, since these timestamps are functionally identical, the code for this should be removed. Any tests verifying timestamps should verify the locial equality, not that the value is the same.