Revert "eb-6895: fixed salespro page to use username in api call (formerly guest_xpedx)"

This reverts commit 40a7cac25ab239d56060000cebe896a241173ce4.
eb-6895: fixed salespro page to properly handle null customer list

added defensive check to prevent api call with null user id, which would return all customers
removed dead code from AjaxGetSalesProCustomersListAction
Merge remote-tracking branch 'upstream/hardening_r15' into hardening_r15