Allow setting maxclientcnxns

[naude-r]

Description

We require to set additional config, specifically maxClientCnxns.

Importance

Currently we cannot deploy more services as ZK is refusing connections with:
Error accepting new connection: Too many connections from /10.42.0.1 - max is 60

Suggestions for an improvement

Either add additional config options during deploy time, or add a user configurable configmap. the configmap can be merged with the fixed settings provided by the operator.

See also #3