[stable/grafana] Make extraVolumeMounts[].existingClaim optional

[catac]

Make extraVolumeMounts[].existingClaim optional so that extraVolumeMounts can be used in conjunction with extraContainerVolumes. Also, provide an example in README.md on how to use both, in order to trust system certificates in the Grafana container.

Signed-off-by: Catalin Cirstoiu Catalin.Cirstoiu@gmail.com

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• DCO signed
• Chart Version bumped
• Variables are documented in the README.md
• Title of the PR starts with chart name (e.g. [stable/mychartname])

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Hi @catac. Thanks for your PR.

I'm waiting for a helm member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[davidkarlsen]

This chart is deprecated: #23662
Please submit PRs against: https://github.com/grafana/helm2-grafana