Jupyter fix hostname editing and remove extra load balancer

What does this MR do?

Fixes #62686 (closed), #59740 (closed)

62686 - While user is editing the Hostname field we would overwrite it with our default hostname value. Fixed it to prioritise user supplied hostname value.

59740 - Jupyter helm chart creates a load balancer by default. We don't need it since we already have a load balancer for the cluster. Extra load balancer also means additional cost to users. Replaced the extra load balancer with NodePorts. Reference: https://github.com/jupyterhub/jupyterhub/issues/1764#issuecomment-377328525

Does this MR meet the acceptance criteria?

Conformity

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Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

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