Make database queries before starting the browser

When we perform database queries in tests after the process running the
browser has started, we sometimes get failures in our test suite due to
both the tests and the browser accessing the database at the same time.

spec/system/admin/poll/booths_spec.rb

@@ -13,7 +13,7 @@ describe "Admin booths", :admin do
   end
 
   scenario "Index" do
-    3.times { create(:poll_booth) }
+    booths = 3.times.map { create(:poll_booth) }
 
     visit admin_root_path
 
@@ -22,7 +22,6 @@ describe "Admin booths", :admin do
       click_link "Booths location"
     end
 
-    booths = Poll::Booth.all
     booths.each do |booth|
       within("#booth_#{booth.id}") do
         expect(page).to have_content booth.name

spec/system/admin/poll/polls_spec.rb

@@ -212,6 +212,7 @@ describe "Admin polls", :admin do
         booth.booth_assignments.each do |booth_assignment|
           3.times { create(:poll_officer_assignment, booth_assignment: booth_assignment) }
         end
+        officers = Poll::Officer.all
 
         visit admin_poll_path(poll)
 
@@ -219,7 +220,6 @@ describe "Admin polls", :admin do
 
         expect(page).to have_css ".officer", count: 3
 
-        officers = Poll::Officer.all
         officers.each do |officer|
           within("#officer_#{officer.id}") do
             expect(page).to have_content officer.name