helm: add lifecycle preStop hook & startupProbe, fix port number

[nefelim4ag]

Summary:

• Allow define lifecycle hooks & add a working example
• Allow override termination gracePeriod
• Allow defining startupProbe
• Fix port number in values

Motivation and Context

Without a lifecycle preStop hook autoscaling is a huge problem (pod will die - test will fail), so just add instrumentation to define one and change the termination grace period.

startupProbe - just for observability purposes, the pod will be shown as ready only when it ready to work

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

#1592

[diemol]

Could you please update your fork and also update the values in Chart.yaml?

[diemol]

Left some comments.

[brainiac84]

@nefelim4ag mind to check a few suggestions, thanks

[diemol]

Thank you, @nefelim4ag!