update chart to be GitOps ready

[RenePinnow]

Summary

• give the option to overwrite random string from configmap else applications like argocd will infinity sync because there always a diff

• give the option to provide secrets from external because storing secret data like passwords in git is an anti pattern.

• remove replicas if ha is enabled. The number of replicas is calculate by hpa else there is a diff between git and the cluster state.

Ticket Link

Fixes https://github.com/mattermost/mattermost-helm/issues/261

[mattermod]

Hello @RenePinnow,

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[RenePinnow]

/check-cla

[cpanato]

@RenePinnow thanks for the PR can you update it and fix the conflict?

[RenePinnow]

@cpanato Conflicts are solved.

[emilyacook]

Thanks for participating in Hacktoberfest! You can claim your sticker set here: https://get.printfection.com/hacktober21/4144583267 @RenePinnow

[mattermod]

This PR has been automatically labelled "stale" because it hasn't had recent activity. A core team member will check in on the status of the PR to help with questions. Thank you for your contribution!

/cc @jasonblais @jfrerich @emilyacook

[RenePinnow]

@cpanato Why was this never merged?

[cpanato]

@cpanato Why was this never merged?

there is a conflict that needs to be addressed

[RenePinnow]

@cpanato I updated my fork again on the newest version. Can you please check and merge. I would like to update mattermost chart and would be nice if it is gitops ready.

[cpanato]

there is a lint issue

charts/mattermost-enterprise-edition/Chart.yaml
  40:47     error    no new line character at the end of file  (new-line-at-end-of-file)

also can you squash the commits?

[RenePinnow]

@cpanato Squashed my commits and fixed the issue.

[cpanato]

thanks @RenePinnow for the PR

I will redirect to @spirosoik and @stylianosrigas for review and to sync the merges

[spirosoik]

@RenePinnow looks good to me thanks a lot

[RenePinnow]

@spirosoik can you please merge it?