[lgtm-distributed] Add Grafana OnCall to the chart dependencies.

[Sheikh-Abubaker]

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Fixes #2698

[timberhill]

This is very nice, is there anyone else that could review this? @zalegrala

[zalegrala]

Not sure who maintains this chart. I don't see owners in .github/CODEOWNERS

[timberhill]

@zalegrala I have created it and asked to add myself to the list of maintainers in the chart, but nothing about codeowners. I guess it would be good to add 2+ people. Here is the initial PR, which was reviewed by @zanhsieh (who might have some thoughts on this).

I am not part of the org, so not sure where to go from here :)

[Sheikh-Abubaker]

@timberhill if maintainers are needed I could come up as one!