N+1 queries in kb_overview_rows() function

[escattone]

The kb_overview_rows function within kitsune.dashboards.readouts contains multiple N+1 queries -- where N can be quite large -- which should be folded into the main docs query as annotations:

• current_revision
• ready_for_l10n
• unapproved_revs
• transdoc
• transdoc.is_outdated()

[escattone]

QA Notes

• The following columns need to be verified that they haven't changed:
  • Needs Update
  • Status
• The Ready for L10N column is included too, but would be verified as part of Ready for L10N column on KB dashboard should reflect only the last normal or major revision #1258.

[emilghittasv]

I can confirm that no regressions were introduced with any of the fields available inside the Knowledge Base Dashboard.

Moving this ticket inside the release column.