[services] Backup - Fix missing hash in unit tests

Summary:
Depends on D4502
Fixing missing hash parameter in LogItem initialisation in generateLogItem function

Test Plan: cd services && yarn run-unit-tests backup

Reviewers: tomek, karol

Reviewed By: tomek, karol

Subscribers: ashoat, tomek, adrian, atul, karol, abosh

Differential Revision: https://phab.comm.dev/D4503