Remove custom informers from InstaScale

[anishasthana]

We have custom informers set up for InstaScale to watch events on appwrappers. As far as I can tell, the informer logic isn't doing anything special -- we should be able to just rely on the default reconcilation loop. Using the inbuilt controller-runtime for for the runtime should suffice. Refer to https://github.com/opendatahub-io/odh-model-controller/blob/main/controllers/inferenceservice_controller.go#L93 for a simple example.

This will reduce the complexity of our code

https://github.com/project-codeflare/instascale/blob/main/controllers/appwrapper_controller.go#L135-L148