Make AAC-w/o-description WPT a mozilla-specific WPT
Due to the ongoing discussion in issue 832 [1], which has not yet
reached a consensus among all parties, the AAC-without-description WPT
introduced in the previous patch should be relocated to the mozilla
folder under WPT. This ensures that the test remains specific to Mozilla
and avoids unintentionally causing failures in other browers' test
suites.
Differential Revision: https://phabricator.services.mozilla.com/D222712
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1917721
gecko-commit: c81481c06eac3165b72e7bb2c3040a48b3994a0a
gecko-reviewers: media-playback-reviewers, padenot