Rely on epic object to sync data to work item instead of params

What does this MR do and why?

Changing the approach, that we take on synching data to work item, when an epic is created or updated. Instead of relying on params, we can sync all attributes to the work item all the time. This does not change the number of DB insert/update statements as AR is smart enough to exclude attributes that did not change, and also it may not even update the work item if it did not change at all.

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