Bug 31020: Fix PassItemMarcToXSLT in system preferences description

Bug 31020: Fix PassItemMarcToXSLT in system preferences description

Bug 28373 added system preference PassItemMarcToXSLT is referenced is all XSLT system preferences.
But it only applies on results pages.
The only use in perl code is in C4::Search :
 > $marcrecord->delete_fields( @fields ) unless C4::Context->preference('PassItemMarcToXSLT');

I've tested by adding in all XSLT files :
  <strong>ITEMS <xsl:value-of select="count(marc:datafield[@tag=952])"/> </strong>
Number of items only appears in OPAC and staff interface results pages.

In fact only search pages get MARC record from search engine, in which items datas have been embedded for indexing.
In other pages MARC record does not embed items datas.

This patch adds "MARC21 952, UNIMARC 995" to be explicit we talk about
MARC datas not item tags build in XML recieved by XSLT.

Test plan :
1) Apply patch
2) Search for PassItemMarcToXSLT in system preferencies
3) Look at description of PassItemMarcToXSLT
4) Check PassItemMarcToXSLT only apprears in OPACXSLTResultsDisplay and XSLTResultsDisplay

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>