[native] Rename promises to cleanupPromises at end of uploadFile(...)
Summary:
There are a lot of promises in uploadFile(...)... figured giving this "section" of them a more descriptive name.
Depends on D4980
Test Plan: NA, simple rename
Reviewers: abosh, jacek, tomek, ashoat
Reviewed By: abosh
Differential Revision: https://phab.comm.dev/D4981