Add sandesh_send_rate_limit parameter

Related-Bug: PROD-29404 (PROD:29404)

Generators of big environments with high traffic and modification requests
can generate huge amount of sandesh messages. It can cause oveloading
and high resource consumption of analytics services.
Amount of sandesh messages can be decreased using
`sandesh_send_rate_limit`.

Change-Id: Idf6055c57e5ca5d2b608ee59ad2c104daadc5c0a
18 files changed