[v2] Network Console Collector should purge inferred records when their parent is purged.

[c-kruse]

I had missed a few cases that causes some confusing behavior when a site comes and goes:

• inferred processes (site-client/site-server) should be removed with their parent SiteRecord
• process|processgroup|sitepairs similarly should be removed along with the last process record (or just the process/group/site?)