A3: permission.can warnings and potential permission check escape for pieces relationship built-in filters

[myovchev]

Somewhat related with #3626

The same console warning as described in the linked issue above is present without any custom projections but using the piece built in relation filter (think of articles filtered by a tag). The strange part is it is only present when no user is logged in.

A demo repo reproducing the problem: https://github.com/myovchev/apos-issue-3626
In order to reproduce: install, create an article, assign a tag, create and navigate to an article page type, click the tag, logout and look at the console logs.

The main suspect: https://github.com/apostrophecms/apostrophe/blob/main/modules/%40apostrophecms/schema/index.js#L2180
but it doesn't explain (to me) why the warning is present only in non-logged-in state.