DEV: Use the type: :multisite spec setting (#9245)

Fixes recent spec flakiness.

Also includes:
DEV: Prevent accidental exit from specs

spec/requests/uploads_controller_spec.rb

@@ -401,10 +401,7 @@ describe UploadsController do
           expect(response.code).to eq("403")
         end
 
-        context "when running on a multisite connection" do
-          before do
-            Rails.configuration.multisite = true
-          end
+        context "when running on a multisite connection", type: :multisite do
           it "redirects to the signed_url_for_path with the multisite DB name in the url" do
             freeze_time
             get upload.short_path