Add e2e tests for webhooks support

[camilamacedo86]

The support to allow ClusterExtensions with webhooks was added in: #1914. The goal of this task is to cover this feature with e2e tests.

[camilamacedo86]

@perdasilva were you working on it?
I think we have it done right?

[camilamacedo86]

Closing it. It is done