Investigate adding more shards for increased performance for single node deployments

[dianabarsan]

Describe the performance issue
Checking an additional path for options for vertically scaling a CHT instance by adding more cores and using a single node CouchDb, since certain processes (like view indexing) are limited by shard count.
We have not seen an obvious performance improvement when vertically scaling single node couchdb without adding multiple shards.

Describe the improvement you'd like
Check whether doubling shard count and doubling CPU count increases performance when querying while documents are pushed to the instance.

Measurements
TBD.