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
+        context "when running on a multisite connection", type: :multisite do
-          before do
-            Rails.configuration.multisite = true
-          end
           it "redirects to the signed_url_for_path with the multisite DB name in the url" do
             freeze_time
             get upload.short_path

spec/services/inline_uploads_spec.rb

@@ -691,10 +691,7 @@ RSpec.describe InlineUploads do
         MD
       end
 
-      it "should correct image URLs in multisite" do
+      it "should correct image URLs in multisite", type: :multisite do
-        begin
-          Rails.configuration.multisite = true
-
         md = <<~MD
         https:#{upload2.url} https:#{upload2.url}
         #{URI.join(SiteSetting.s3_cdn_url, URI.parse(upload2.url).path).to_s}
@@ -712,9 +709,6 @@ RSpec.describe InlineUploads do
         ![some image](#{upload2.short_url})
         ![](#{upload3.short_url})
         MD
-        ensure
-          Rails.configuration.multisite = false
-        end
       end
     end
   end

spec/tasks/redis_spec.rb

@@ -2,19 +2,13 @@
 
 require 'rails_helper'
 
-RSpec.describe "Redis rake tasks" do
+RSpec.describe "Redis rake tasks", type: :multisite do
   let(:redis) { Discourse.redis.without_namespace }
 
   before do
-    @multisite = Rails.configuration.multisite
-    Rails.configuration.multisite = true
     Discourse::Application.load_tasks
   end
 
-  after do
-    Rails.configuration.multisite = @multisite
-  end
-
   describe 'clean up' do
     it 'should clean up orphan Redis keys' do
       active_keys = [

spec/tasks/uploads_spec.rb

@@ -43,7 +43,7 @@ RSpec.describe "tasks/uploads" do
     context "when the store is internal" do
       it "does nothing; this is for external store only" do
         Upload.expects(:transaction).never
-        invoke_task
+        expect { invoke_task }.to raise_error(SystemExit)
       end
     end