Bug 10465: remove useless reference to fields 780 and 785 in UNIMARC XSLT files

UNIMARCslim2OPACDetail.xsl and UNIMARCslim2intranetDetail.xsl contained
references to 780 and 785 fields, that exist in MARC21 but not in UNIMARC.

This patch remove the code related to 780 and 785 fields. No effect should
be visible.

To test : in a UNIMARC Koha
1. Be sure that OPACXSLTDetailsDisplay, OPACXSLTResultsDisplay,
   XSLTDetailsDisplay and XSLTResultsDisplay sysprefs are set to "default"
2. Apply the patch
3. Search some records in staff interface : the list view and the detail
   view must be exacty the same as before you apply the patch.
4. search some records in OPAC : the list view and the detail view must
   be exactly the same as before you apply the patch.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Comment: No diplay change, no koha-qa errors.
Removes what can't be displayed.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Checked detail pages in OPAC and intranet still display correctly
and without errors.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>