[BUG] Pod update failed with fluid webhook injection enabled

[TrafalgarZZZ]

What is your environment(Kubernetes version, Fluid version, etc.)

Describe the bug
Pod update failed with fluid webhook injection enabled

What you expect to happen:

Pod can be successfully updated.

How to reproduce it

1. enable fluid webhook injection

kubectl label namespace default fluid.io/enable-injection=true

2. Run any pod without Fluid dataset pvc

kubectl run --image=nginx nginx

3. Try to edit the nginx pod spec.image but failed to pass API server validation.

kubectl edit pod nginx

Additional Information