Add RTL tests to `@shared/UserOrgSelect.jsx`

Add a test to @shared/UserOrgSelect.jsx using the RTL framework.

Acceptance Criteria

[ ] Colocate test file to @shared/UserOrgSelect.test.jsx
[ ] Test the label is showing as expected
[ ] Test the error message shows when the select has been touched and has an error
[ ] Test the options are available
[ ] Test the default option Please select an organization on initial render
[ ] Test the select change works