Use SyncServiceTokenWorker to refresh ServiceAcessToken

What does this MR do and why?

In !136078 (merged) we introduced SyncServiceTokenWorker and use_sync_service_token_worker feature flag.

In this Mr, we are using use_sync_service_token_worker to switch between using SyncServiceTokenWorkerand SyncSeatLinkWorker

Also, if ff is enabled, we will not store the ServiceAccessToken within SyncSeatLinkRequestWorker. The token is still sent there only for backward compatibility reasons

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