Make reverse proxy send error messages to klog and to virtctl

[EduardGomezEscandell]

What this PR does / why we need it: Upload proxy uses the httputil.ReverseProxy.

When httputil.ReverseProxy fails, it sends a message down the standard library's default logger. This can be seen in the pod's log but the client simply receives a 5xx error and no context.

This PR redirects messages away from the standard logger and into both the k8s logger and the client.

Changes in virtctl output BEFORE

unexpected return value 502,

AFTER

unexpected return value 502, error in upload-proxy: http: proxy error: dial tcp 10.101.34.134:443: connect: connection timed out

Changes in upload-proxy logs BEFORE

2024/05/09 16:30:08 http: proxy error: dial tcp 172.30.111.109:443: connect: connection timed out

AFTER

E0605 11:02:45.551559       1 uploadproxy.go:323] Error in reverse proxy: http: proxy error: dial tcp 10.101.34.134:443: connect: connection timed out

Which issue(s) this PR fixes https://issues.redhat.com/browse/CNV-41624

Special notes for your reviewer:

Release note:

Improve error reporting in upload-proxy

[EduardGomezEscandell]

To exercise this fix you need a VM image, then you can run this script:

IMAGE=./cirros-0.6.2-x86_64-disk.img

# Start cluster
make cluster-up
make cluster-sync

# Patch cluster (Solved in https://github.com/kubevirt/containerized-data-importer/pull/3306)
host_port=$(./cluster-up/cli.sh ports uploadproxy | xargs)
override="https://127.0.0.1:$host_port"
kubectl patch cdi cdi --type merge -p '{"spec": {"config": {"uploadProxyURLOverride": "'"$override"'"}}}'

# Break the uploadproxy
cat << EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata: 
  name: default-deny-ingress
spec: 
  podSelector: {}
  policyTypes: 
  - Ingress
EOF

# Exercise the error
virtctl image-upload dv hello-example --size=1Gi --image-path "${IMAGE}" --force-bind --insecure

Keep it mind it takes a while to fail because it keeps retrying.

[EduardGomezEscandell]

/cc @awels

[awels]

/retest

[EduardGomezEscandell]

/retest

[EduardGomezEscandell]

/cc @awels

[awels]

/approve

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: awels

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