1053156 - fix slowness in errata indexing

product_id does not seem to be used anywhere and its fetching
was very poorly optimized and did not seem to be used as part of
a search.

Did a grep/scan of code and tested out these pages/actions:

* Dashboard
* CVD publish
* CV Refresh
* Changeset promote
* Content search
Merge pull request #3569 from jlsherrill/errata_index

1053156 - fix slowness in errata indexing