[BUG] gatekeeper is deployed without PDB

[mblaschke-daimlertruck]

Describe the bug
gatekeeeper must de deployed with a sane PDB as it's used in a validationwebhookconfiguration. A GA feature should be deployed with best practises in mind.

To Reproduce
n/a

Expected behavior
AKS should ensure that the validationwebhook is running all the time and so gatekeeper is deployed with a PDB.

Screenshots
n/a

Environment (please complete the following information):

• AKS 1.30.5

Additional context
Add any other context about the problem here.

[microsoft-github-policy-service]

Action required from @aritraghosh, @julia-yin, @AllenWen-at-Azure

[microsoft-github-policy-service]

Issue needing attention of @Azure/aks-leads

[microsoft-github-policy-service]

Issue needing attention of @Azure/aks-leads