Remove stale reference to aria-labeledby [sic] in accname/name/comp_labelledby.html

[cookiecrook]

Remove stale references to aria-labeledby [sic] in accname/name/comp_labelledby.html

<a href="#" aria-labeledby="nested_image_label2">
    link1<!-- this text is skipped because of aria-labeledby -->

That should have been removed with #170 but it was intended to be temporary... now that wpt #50392 won't be reverted, this editorial removal should be its own PR.

[cookiecrook]

Clarifying for any newcomers that want to fix this... The whole, currently inactive subtest should be removed, not just the snippet I referenced above. Possibly more if any other subtests in the repo reference the misspelled version of aria-labeledby.