Issue 572: Enable external option to client service

[idolaman]

Change log description

Adds the option to use external ZooKeeper in ClientService

Purpose of the change

Fixes #572

What the code does

The code uses the same logic as AdminServerService boolean external field. in ClientService, to expose client-service outside
the cluster, using LoadBalancer service type.

How to verify it

System tests must pass, when clientService.external is true, client service in kubernetes type needs to be LoadBalancer (this test added).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (28d1f69) 85.12% compared to head (2ca1a87) 85.13%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #576      +/-   ##
==========================================
+ Coverage   85.12%   85.13%   +0.01%     
==========================================
  Files          12       12              
  Lines        1613     1615       +2     
==========================================
+ Hits         1373     1375       +2     
  Misses        155      155              
  Partials       85       85              

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[almogtavor]

@anishakj can you check this out? This is a quite needed feature