Update prow config with the latest folders

[andreyvelich]

I updated prow config with the latest Suggestion folders.

Also, I added examples/v1alpha3/*.yaml folder to prow.
I think we should trigger e2e test, if we change examples.

And I added these folders to postsubmit, to be consistent with presubmit:

test/e2e/v1alpha3/*
manifests/v1alpha3/*
scripts/v1alpha3/*

/assign @johnugeorge @gaocegege

[kubeflow-bot]

This change is 

[johnugeorge]

/lgtm

[johnugeorge]

/approve

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