Use raw history/matching client in history task executor

[yycptt]

History task processing framework already has it's own retry policy re. task processing failures. Using retryable history/matching client for talking to remote service when processing tasks are unnecessary and will cause tasks to retry while holding the goroutine.

This issue is most obvious when those client requests are getting rate limited, which is a retryable error and is retried slowly (backoff.ThrottledRetry) by the history/matching retryable client while holding the goroutine.