set some loki retention policy

[jacksonloper]

I think we store logs indefinitely right now. That's probably too long 😂 . We should set some limit.

[3uzbcqje]

@jacksonloper I think we can close this issue, because we have retention settings here: https://github.com/Equal-Vote/argocd/blob/main/applications/loki/values.yaml#L38