Remove new XML test cases added by e7192486d.

Remove new XML test cases added by e7192486d.

These turn out to produce libxml2-version-dependent error reports.
They aren't adding value that would justify dealing with that,
so just remove them again.  (I had in fact guessed wrong about
what versions matching xml_2.out would produce, but it doesn't
matter because there are other discrepancies.)

Per buildfarm.

Discussion: https://postgr.es/m/trinity-b0161630-d230-4598-9ebc-7a23acdb37cb-1720186432160@3c-app-gmx-bap25
Discussion: https://postgr.es/m/trinity-361ba18b-541a-4fe7-bc63-655ae3a7d599-1720259822452@3c-app-gmx-bs01