Move initial_sync suite of tests into its own tasks in sys-perf project

We recently introduced a large number of tests related for initial_sync. They are added as part of the core_workload suite. The large number of addition made reading existing data difficult. These new tests also need to go through a vetting period for us to make adjustment for automatic analysis.

We should break this suite of tests away from the core_workload task and make them run in a separate task. This will require reworking of the system_perf.yml and likely make some changes to the workload repo.