gardener-controller-manager: Enable the audit policy configmap reference protection by default

[ialidzhikov]

How to categorize this issue?

/area audit-logging control-plane
/kind cleanup

What would you like to be added:
With #3117 the reference protection for audit policy configmaps was disabled by default because of backwards-compatibility reasons:

Hence, let's disable it by default for now to allow everybody to adapt their workflows appropriately. We can revisit the topic and enable it by default again/remove the configuration option as whole after a couple release.

We can enable the reference protection and finally remove the configuration option.

Why is this needed:
To have the reference protection enabled by default.

Tasks:

• Enable the audit policy configmap reference protection by default (but still allow to be configured and disabled) -> gardener-controller-manager: Enable the audit policy configmap reference protection by default #5426
• Clean up the .controllers.shootReference.protectAuditPolicyConfigMaps configuration option (hence do not allow the protection to be disabled) -> gardener-controller-manager: Remove the audit policy configmap reference protection option #5525

[ialidzhikov]

/assign