Fix `rake db:seed_fu` not doing anything in CI

The default behavior of seed_fu is to load the fixtures using the RAILS_ENV
environment.  In CI, since we set RAILS_ENV=test, nothing is ever
loaded. Instead of `rake db:seed_fu`, use `rake gitlab:setup`, which sets up
MySQL properly with limits.

Closes #41517

.gitlab-ci.yml

@@ -517,10 +517,12 @@ db:rollback-mysql:
     SIZE: "1"
     SETUP_DB: "false"
     CREATE_DB_USER: "true"
+    FIXTURE_PATH: db/fixtures/development
   script:
     - git clone https://gitlab.com/gitlab-org/gitlab-test.git
        /home/git/repositories/gitlab-org/gitlab-test.git
-    - bundle exec rake db:setup db:seed_fu
+    - scripts/gitaly-test-spawn
+    - force=yes bundle exec rake gitlab:setup
   artifacts:
     when: on_failure
     expire_in: 1d

lib/gitlab/seeder.rb

@@ -8,7 +8,7 @@ end
 module Gitlab
   class Seeder
     def self.quiet
-      mute_mailer unless Rails.env.test?
+      mute_mailer
 
       SeedFu.quiet = true
 

scripts/create_mysql_user.sh

 #!/bin/bash
 
 mysql --user=root --host=mysql <<EOF
-CREATE DATABASE IF NOT EXISTS gitlabhq_test;
+CREATE DATABASE IF NOT EXISTS gitlabhq_test DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
 CREATE USER IF NOT EXISTS 'gitlab'@'%';
 GRANT ALL PRIVILEGES ON gitlabhq_test.* TO 'gitlab'@'%';
 FLUSH PRIVILEGES;