Fix flaky / incorrect tests

The following tests are failing nearly all or all the time:

rspec ./spec/models/organization_spec.rb:407 - https://github.com/rubyforgood/human-essentials/actions/runs/22827473629/job/66210053824?pr=5513

rspec ./spec/requests/reports/donations_summary_spec.rb:17 - https://github.com/rubyforgood/human-essentials/actions/runs/22827293217/job/66209592199?pr=5513

