Featured Content Front page vs Posts page ambiguity

This came up in 2611402-t.

Normally when the "Display tag content in all listings" option is unchecked in the Customizer, it removes any posts from the frontpage feed that is tagged with the Featured Post tag. This is working perfectly.

However, if the front page is set to a static front page rather than Latest Posts, despite the box still being unchecked, the posts now appear in the post feed on the Blog page.

This seems to be by design: https://github.com/Automattic/jetpack/blob/86e4891c3c4f965c89e62347426f5bbeda415dc8/modules/theme-tools/featured-content.php#L275-L278

I don't see any immediately obvious reason why we would want to only exclude the posts on the Front Page but not on the Posts Page. On https://jetpack.com/support/featured-content/ we say that it's for the front page only, but this functionality can be useful for any Posts Page, not just the Front Page of a site, so I think we should remove the the code linked to above.

The behavior is implemented in modules/theme-tools/featured-content.php around lines 275-278; read that conditional and the linked Featured Content support guidance first. Reproduce the static-front-page and Latest Posts cases, then verify that an unchecked “Display tag content in all listings” setting excludes Featured Post-tagged posts from both feeds.

Written by the indexing model from the issue text.