Bug 40978: Remove warnings from Budgets.t

If no shipment_budget is set then undef is set as key of the hashref
which generates a warning:
  Use of uninitialized value $row[0] in hash element at /usr/lib/x86_64-linux-gnu/perl5/5.40/DBI.pm line 2122.

Later we only access the hashref by budget_id, so this change seems
safe.

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit f073262263)
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>

C4/Budgets.pm

@@ -755,6 +755,7 @@ sub GetBudgetHierarchy {
             SELECT shipmentcost_budgetid as budget_id,
                 SUM(shipmentcost) as shipmentcost
             FROM aqinvoices
+            WHERE shipmentcost_budgetid IS NOT NULL
             GROUP BY shipmentcost_budgetid
             |, 'budget_id'
         );