provide option to configure agent install strategy

[TheRealHaoLiu]

previous strategy enable managed-serviceaccount addon on all managedclusters, user is not able to disable the addon by removing the ManagedClusterAddon resource

the proposed change add a new option agent-install-all to the binary

if agent-install-all == true enable agent on all managed clusters
if agent-install-all == false do not enable agent by default and the addon will only be enabled when a ManagedClusterAddon is created in the cluster namespace and will be disabled when the ManagedClusterAddon is deleted

example ManagedClusterAddon

apiVersion: addon.open-cluster-management.io/v1alpha1
kind: ManagedClusterAddOn
metadata:
  name: managed-serviceaccount
  namespace: hao-aks
spec:
  installNamespace: open-cluster-management-managed-serviceaccount

[qiujian16]

We should introduce a flag for this

[yue9944882]

i think so, let's add an flag

[TheRealHaoLiu]

Good plan, I will add a flag

What should be the default behavior?

[qiujian16]

Let's set the default behavior as-is

[TheRealHaoLiu]

updated the default value in the chart

[TheRealHaoLiu]

/retest

[qiujian16]

/approve
/lgtm

[openshift-ci]

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