Remove "contentinfo region scoped to main element is generic" WPT test.

Per the HTML-AAM spec, the contextual role restriction only applies to the <footer> element, not to any other instance of the ARIA contentinfo role.
Even though <footer> maps to contentinfo, contentinfo does not necessarily map to <footer>.
Thus, this test is incorrect.

Differential Revision: https://phabricator.services.mozilla.com/D201928

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1878363
gecko-commit: 5c67e50b735884a798f9a9c29b9117a1fc696ebe
gecko-reviewers: nlapre

wai-aria/role/contextual-roles.html

@@ -76,7 +76,6 @@
     see: https://w3c.github.io/html-aam/#el-footer-ancestorbody -->
     <main>
         <footer data-testname="footer element scoped to main element is generic" class="ex-generic">x</footer>
-        <div role="contentinfo" data-testname="contentinfo region scoped to main element is generic" class="ex-generic">x</div>
     </main>
 
     <footer data-testname="footer scoped to body element is contentinfo" data-expectedrole="contentinfo" class="ex">x</footer>