After 4.4 we switched mongo::Document to use lazy shredding instead of eager shredding. If a customer has a large group key over large documents with potentially missing fields this can result in lots of linear look ups for each field resulting in O(n^2) type behavior. where N is the number of fields in a document. The goal of this ticket is to make a temp fix this issue for 5.0 in the classic engine since SERVER-79548 should fix this for SBE. This ticket does not make any changes to the group or project stage but adds a mechanism to opt in to the old eager document shredding