[lib] Rename reduceThreadUpdates => generateOpsForThreadUpdates
Summary:
More accurately reflects the behavior of the function
Depends on D4197
Test Plan: No other occurences of "reduceThreadUpdates" in the codebase
Reviewers: def-au1t, palys-swm
Reviewed By: palys-swm
Subscribers: ashoat, Adrian, yayabosh
Differential Revision: https://phab.comm.dev/D4198