[native] extract processing store operations to separate function

Summary:
In future there will be a need to call this from more places - to be precise here.
This action can not be moved lower in file to use the same code as previously as it's only-native and should be finalized before base reducer.

Test Plan: Check if operations are processed properly

Reviewers: tomek, marcin

Reviewed By: tomek

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D7421