Fix time zone flakiness in distribution by county specs

[coalest]

Description

Apparently some of the specs I added were flaky in two different ways 🙃

Example of it failing in CI

Error message:

  1) Distributions by County handles time ranges properly works for prior year
     Failure/Error: expect(page).to have_css("table tbody tr td", text: "25", exact_text: true, count: 4)
       expected to find visible css "table tbody tr td" with exact text "25" 4 times but there were no matches. Also found "County 14", "50", "$525.00", "County 13", "50", "$525.00", "County 16", "50", "$525.00", "County 15", "50", "$525.00", "Unspecified", "0", "$0.00", which matched the selector but not all filters. 

     [Screenshot Image]: /home/runner/work/human-essentials/human-essentials/tmp/capybara/failures_r_spec_example_groups_distributions_by_county_handles_time_ranges_properly_works_for_prior_year_55.png


     # ./spec/system/distributions_by_county_system_spec.rb:58:in `block (3 levels) in <top (required)>'

Pretty sure this is a time zone issue. We query times in Los Angeles time zone during tests. But we were saving times in UTC to the database.

Type of change

• Fix flaky spec

How Has This Been Tested?

Locally