[baseserver] Change default metrics port to 9502 to not clash with kube-rbac-proxy

[easyCZ]

Normally, we expose kube-rbac-proxy for metrics on port 9500. With #10099 we removed listening on localhost to avoid a pitfall where listening on localhost would be inaccessible from outside the container.

In this PR, the default port is updated to not clash with 9500 which we commonly use for metrics through kube-rbac-proxy. Currently, only usage is by public-api-server (which crash-loops due to this) and content-service which doesn't have kube-rbac-proxy deployed so this change is safe.

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[sagor999]

when we switch to baseserver, does it mean we will need to update metrics port on deployment to match new port? 🤔

[easyCZ]

@sagor999 for public api, the installer already uses the the cost that's changed in this PR so there's no change needed. For scraping, we parametrize the proxy url for Kube-rbac-proxy so there no change is needed either. This should work without requiring additional changes

[aledbf]

We need to rollback this change. The issue here is not the collision but the Prometheus listening should happen in localhost, that way the traffic can go from kube-rbac-proxy to the localhost port