Major Helm refactor

[duhow]

Description of the change

I wanted to deploy Rudderstack in my Kubernetes cluster, but faced lots of issues.
So I spent the whole day tweaking the Helm Chart, cleaning up some stuff, fixing some settings...

Here's a list of changes (not all included):

• Remove subchart downloaded dependencies (old postgresql)
• Migrate transformer chart into rudderstack
• Add bitnami/postgresql Chart dependency
• Move to subfolder charts/rudderstack so in the future you can generate Helm Repository and publish into ArtifactHub or others.
• Migrate most of values ENV into Secret and ConfigMap, allow to customize by Helm values
• Replace livenessProbe by startupProbe
• Change wait-for commands by initContainer
• Update config enableStats matching telegraf status (stop spamming cannot connect to statsd)
• Rename values keys to standard Chart names (eg. version -> tag)
• Update appVersion to match latest fix version 1.43.1
• Bump Chart version from 0.7.0 to 0.8.0

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers mentioned in a comment
• Changes have been reviewed by at least one other engineer
• Issue from task tracker has a link to this pull request

[contributor-support]

Thank you @duhow for contributing this PR.
Please sign the Contributor License Agreement (CLA) before merging.

[AkhileshK8y]

@duhow Thanks for raising this PR. One of the reasons why we couldn't use postgres charts as dependency here was this. In bitnami charts, replica count is set to 1 if we need multiple backend replica of rudder server then similar number of postgres pods will also be required. Hence we are maintaining our version of postgres charts. Which I do understand is not the best way. You know any way to better it?

[Riqardos]

@duhow Thanks for raising this PR. One of the reasons why we couldn't use postgres charts as dependency here was this. In bitnami charts, replica count is set to 1 if we need multiple backend replica of rudder server then similar number of postgres pods will also be required. Hence we are maintaining our version of postgres charts. Which I do understand is not the best way. You know any way to better it?

Why do we need multiple postgres pods when we are using multiple backend replica? Is it because of performance or we need to have standalone databases with separated data?