[kube-config-manager] Fix updating configmap by a hook

[miklezzzz]

Overview

Updating the addon-operator's configmap by a hook had been broken after one of many refactorings. The module's config values would be updated in the operator's runtime, yet not in the configmap.
This pr mends that functional.

What this PR does / why we need it

Closes #536

Special notes for your reviewer

[miklezzzz]

hook config

bash-5.1# cat modules/001-sysctl-tuner/hooks/test-hook.sh 
#!/bin/bash

if [[ $1 == "--config" ]] ; then
  cat <<EOF
{
  "configVersion":"v1",
  "beforeHelm": 1,
  "afterHelm": 1,
  "afterDeleteHelm": 1
}
EOF
exit 0
fi

binding=$(jq -r '.[0].binding' "${BINDING_CONTEXT_PATH}")
echo "Binding: $binding"
if [[ $binding == "beforeHelm" ]]; then
cat > $CONFIG_VALUES_JSON_PATCH_PATH <<EOF
    [{"op":"add", "path":"/sysctlTuner/param11", "value":"value11"}]
EOF
echo "Patching: $binding"
fi

before

bash-5.1# ./addon-operator module values sysctl-tuner
env: testing2
param11: value11


kubectl get cm addon-operator -o yaml
apiVersion: v1
data:
  global: |
    param12: value12
    test: test
  sysctlTuner: |
    env: testing2
    param11: value11
  sysctlTunerEnabled: "true"
  testModule: |
    val: val1
kind: ConfigMap
metadata:
  name: addon-operator
  namespace: default

after

bash-5.1# ./addon-operator module values sysctl-tuner
env: testing2
param11: value11


kubectl get cm addon-operator -o yaml
apiVersion: v1
data:
  global: |
    param12: value12
    test: test
  sysctlTuner: |
    env: testing2
    param11: value11
  sysctlTunerEnabled: "true"
  testModule: |
    val: val1
kind: ConfigMap
metadata:
  name: addon-operator
  namespace: default

[miklezzzz]

"error":"module hook 'v0.7.104/hooks/test-hook.sh': set kube module config failed: saving patch values in ModuleConfig is forbidden",