Verify staff basket price overrides (#4403)

* 🔒 Verify staff basket price overrides

* 🐛 Fix update patcher test spelling

* 🐛 Apply staff price overrides to promo discounts

* Update ServiceTest.php

* Fix percent promo invoice discount base

* Base % invoice promos on order line totals

* Clarify invoice promo discount comments

tests/Unit/FOSSBilling/UpdatePatcherTest.php

@@ -1384,7 +1384,7 @@ test('applyCorePatches removes retired hook data on non-MySQL drivers and remain
     });
 });
 
-test('retired hook cleanup uses both parameterless portable delete statements', function (): void {
+test('retired hook cleanup uses both portable delete statements without parameters', function (): void {
     withNonMysqlDbDriver(function (): void {
         $listenerStatement = Mockery::mock(PDOStatement::class);
         $listenerStatement->expects('execute')->with([])->andReturnTrue();