Revert "Ensure ITS namespace is declared on TextUnits" (OC-21)

    This reverts commit 19c6ede2a42ee809bd9c730f8b6c92b6e529aed2.
    This commit caused the regression described in OC-21.
OC-21 Unittest (Currently fails)

    This is a unittest for the original problem that was fixed in
    ffbb75e7f and reintroduced when I reverted that commit.
OC-21 - Alternate fix for ffbb75e7f

    This is regex-based, and I don't like it one bit.  However, this fix
    ultimately needs to come from the XLIFF filter, so this is a
    workaround.