Ignore $K_CE_OVERRIDES env variable on Knative environments

The new Knative Eventing version injects a new variable in our deployment that also must be ignored by the comparator: $K_CE_OVERRIDES

Maybe it's time to have a control list of env vars that we control and ignore the rest instead.- I'll bring this to discussion in the next team meeting.-

Forget, now we allow any envs that are not in our control to be there, the operator won't override them any more. See the PR for more details.