Section topics suggestions, round 2

Another, hopefully improved, round of section image suggestions based on section topics.

• section topics suggestions must now also match page entity in addition to topic entity
• more sources (p373 + lead images, in addition to existing p18) are used for section topics suggestions
• kind is renamed to istype-section-topics for such suggestions
• existing image filters are made consistent across page & section (alignment + topics) image suggestions
• beyond-some-threshold-usage filter is being made wiki-dependant to prevent excessive (iconographic) use of valid images from interfering with other wikis
• implemented more accurate confidence values to reflect the assumption that a suggestion matching in multiple sources is likely better than one matching only a subset of those sources

Bug: T330773