Grafana: Payments dashboard log fix & fine tune

@jcalderone This is a JSON-blob-only diff for the "Payments" dashboard. It should fix the log panels, make a couple of things a little bit better and probably nothing worse.

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• (tryfix) Switch to Loki datasource;
• Filter requests to metrics instead of all GET;
• Show the last week by default
• Show log times

Interesting and not quickly fixable as it looks like: the GET ... line comes after the result. We might be logging this wrong to begin with, but probably this is some next gen AI line ordering intelligence

Update: Later added:

• Turn on shared crosshair for this dashboard (we might want this on the other dashes too?)
• Semi-transparency for the two lastly edited panels, for the looks