Fix order-dependent test failures

Prevent extra DB connection pools from leaking to succeeding tests and
also improves our connection check initializer so that it works even
with multiple connection pools for the same DB name.

lib/initializer_connections.rb

@@ -12,15 +12,15 @@ def self.raise_if_new_database_connection
     return yield if Gitlab::Utils.to_boolean(ENV['SKIP_RAISE_ON_INITIALIZE_CONNECTIONS'])
 
     previous_connection_counts =
-      ActiveRecord::Base.connection_handler.connection_pool_list(ApplicationRecord.current_role).to_h do |pool|
-        [pool.db_config.name, pool.connections.size]
+      ActiveRecord::Base.connection_handler.connection_pool_list(ApplicationRecord.current_role).map do |pool|
+        pool.connections.size
       end
 
     yield
 
     new_connection_counts =
-      ActiveRecord::Base.connection_handler.connection_pool_list(ApplicationRecord.current_role).to_h do |pool|
-        [pool.db_config.name, pool.connections.size]
+      ActiveRecord::Base.connection_handler.connection_pool_list(ApplicationRecord.current_role).map do |pool|
+        pool.connections.size
       end
 
     raise_database_connection_made_error unless previous_connection_counts == new_connection_counts

spec/lib/initializer_connections_spec.rb

@@ -37,14 +37,13 @@ def block_with_error
       expect { block_with_database_call }.not_to raise_error
     end
 
-    it 'prevents any database connection if SKIP_RAISE_ON_INITIALIZE_CONNECTIONS is false',
-      quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/444962' do
+    it 'prevents any database connection if SKIP_RAISE_ON_INITIALIZE_CONNECTIONS is false' do
       stub_env('SKIP_RAISE_ON_INITIALIZE_CONNECTIONS', 'false')
 
       expect { block_with_database_call }.to raise_error(/Database connection should not be called during initializer/)
     end
 
-    it 'restores original connection handler', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/444963' do
+    it 'restores original connection handler' do
       original_handler = ActiveRecord::Base.connection_handler
 
       expect { block_with_database_call }.to raise_error(/Database connection should not be called during initializer/)

spec/tasks/gitlab/backup_rake_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe 'gitlab:backup namespace rake tasks', :delete, feature_category: :backup_restore do
+RSpec.describe 'gitlab:backup namespace rake tasks', :reestablished_active_record_base, :delete, feature_category: :backup_restore do
   let(:enable_registry) { true }
   let(:backup_restore_pid_path) { "#{Rails.application.root}/tmp/backup_restore.pid" }
   let(:backup_rake_task_names) do