fix: Increase otel-agent CPU request to 20m

[karlkfi]

The limits are being set to request values on autopilot, which has been causing the otel-agent to fail liveness probes and get restarted. This increase should help prevent that.

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[janetkuo]

The cpu request hasn't changed for a few releases. Did we introduce something new in this release that causes the need to increase cpu request/limit on Autopilot?

[karlkfi]

The cpu request hasn't changed for a few releases. Did we introduce something new in this release that causes the need to increase cpu request/limit on Autopilot?

I don't know. All I know is that it's failing on autopilot-rapid, because it's setting CPULimit = CPURequest.
https://cloud.google.com/kubernetes-engine/docs/concepts/autopilot-resource-requests#resource-limits

[karlkfi]

This PR may have increased resource usage of the otel-agent somewhat: #763

The generation metrics label isn't going to Cloud Monitoring, but it does go through the otel-agent and otel-collector.

[janetkuo]

Given that this number will multiply by the number of RSyncs in the cluster, I'd like to avoid increasing it if possible (or keep it to a minimum). Here's our current number: https://cloud.google.com/anthos-config-management/docs/how-to/installing-config-sync#detailed_resource_requests

[karlkfi]

I think risking breakage to keep requirements low is a bad trade-off, but now that the liveness probes are removed, it at least won't cause endless restarts.