[client-app] Remove sudo from benchmark-initial-sync.sh
[client-app] Remove sudo from benchmark-initial-sync.sh

Summary:
We created the process so we can also kill it with no problems. This
makes it easier to automatically run benchmarks without human
intervention.

Test Plan: Run locally

Reviewers: spang, evan, juan

Reviewed By: juan

Differential Revision: https://phab.nylas.com/D4332

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