Fix CRD references for Prometheus operator

[jhosteny]

This commit changed the CRD yaml file names. This can be fixed by pinning to v0.34.0, or changing the referenced filename. I have a change that does the latter if you would like that as a fix. I'd suggest pinning it to v0.34.0 though, and can submit a PR for that instead if desired. There is no tag yet with the newest filenames.