KRACOEUS-8345 added getParentBudget to allow searching

Until PD's can create valid IPs that can fund an award, this isn't fully testable. However, this prevents a stack trace from popping up if you click the search icon next to an award budget period line.
I feel like this is masking a bigger problem. We shouldn't be able to have an AwardBudgetDocument without a budget and a budget shouldn't exist without a budget parent...so what happens that makes this possible?