CI: prometheus - reduce storage amount, length. set resources

What does this MR do?

CI: prometheus - reduce storage amount, length. set resources

We have been seeing a lot of Prometheus "failing" due to memory pressures on the node(s) when in use.

Forcibly set the retention to 1GB over 3d.

Set the resources! They were 0, so it will "always" lose. Ask for 2G, limit to 4G. Observation shows "happy" prometheus at ~2.5G

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