Bug 1763281 serve movie_5.ogv with Content-Type:video/ogg r=media-playback-reviewers...

Bug 1763281 serve movie_5.ogv with Content-Type:video/ogg  r=media-playback-reviewers,padenot

Firefox uses only the first of Partial Content responses to sniff the type,
but falls back to the Content-Type because the initial response is so short.
https://bugzilla.mozilla.org/show_bug.cgi?id=1763277

Firefox behavior weakly arguably conforms with the permitted abort of "read
the resource header" when "a reasonable amount of time has elapsed, as
determined by the user agent",
https://mimesniff.spec.whatwg.org/#read-the-resource-header
but the purpose of the tests is not to test sniffing,
https://github.com/web-platform-tests/wpt/commit/67593065a83156851279d1751fc865131e8dbff9#diff-4cc71e3c53ed088f2f437b1c43d9bec445827f10a4f6dce0615eb0f4e7823e3dR37
so let's keep the results independent of this edge case.

Differential Revision: https://phabricator.services.mozilla.com/D143119