Remove search calls to fetch max seq no for each shard in doc level monitor. Use first call to fetch data from a shard to determinte max seq no.

[eirsep]

Current behaviour

• If there are n indices with m shards each, we first run n*m search calls to simply fetch the max sequence number
  for each shard and then perform the searches which fetch docs from each shard based on last seen seq no. and max seq no.

Optimized behaviour proposed

Change first search request from each shard to fetch all docs in descending order of seq no with filter on `seqno >
That way we are fetching docs and also able to note the sequence number correctly within the same call and avoid the first batch of search calls which simply help determine the sequence number