Fix Sybunt to select mark rows as selected

[eileenmcnaughton]

Overview

Fixes a probably-not-that-recent bug where sybunt custom search does not permit contacts to be marked as selected

Before

Doing a Sybunt custom search & then selecting rows does not increment the 'selected' value

After

The selected value is incremented

Technical Details

With sort_name being retrievable the prevnext cache fails to fill. This is quietly caught - I also changed it to be more noisily caught

Comments

@seamuslee001 found while checking #15820 n& https://lab.civicrm.org/dev/core/issues/1377

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).

[seamuslee001]

@eileenmcnaughton i have tested this and works as expected, i also checked other custom searches and found that the Price Set Custom Search was also an issue

[seamuslee001]

sorry not price set event totals custom search

[eileenmcnaughton]

@seamuslee001 shall we merge this one

[seamuslee001]

Yeh, the event aggregate custom search is the one that is then of issue but its an odd one