[REF] [Export] clean up incorporation of order by & group by into ExportProcessor

[eileenmcnaughton]

Overview

Consolidate all the code required to build the query into one function

Before

All over the place :-)

After

In build Query

Technical Details

Part of larger code cleanup

Comments

[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).

[eileenmcnaughton]

test this please

[colemanw]

Test failure unrelated.
Merging based on code review & passing tests.