Move package tasks and fixtures to core

- Move package rake tasks to core
- move dev fixtures to core
- move package object store helpers to core

ee/spec/support/helpers/ee/stub_object_storage.rb

-# frozen_string_literal: true
-module EE
-  module StubObjectStorage
-    def stub_packages_object_storage(**params)
-      stub_object_storage_uploader(config: ::Gitlab.config.packages.object_store,
-                                   uploader: ::Packages::PackageFileUploader,
-                                   remote_directory: 'packages',
-                                   **params)
-    end
-
-    def stub_dependency_proxy_object_storage(**params)
-      stub_object_storage_uploader(config: ::Gitlab.config.dependency_proxy.object_store,
-                                   uploader: ::DependencyProxy::FileUploader,
-                                   remote_directory: 'dependency_proxy',
-                                   **params)
-    end
-
-    def stub_object_storage_pseudonymizer
-      stub_object_storage(connection_params: Pseudonymizer::Uploader.object_store_credentials,
-                          remote_directory: Pseudonymizer::Uploader.remote_directory)
-    end
-  end
-end

spec/support/helpers/stub_object_storage.rb

 # frozen_string_literal: true
 
 module StubObjectStorage
+  def stub_packages_object_storage(**params)
+    stub_object_storage_uploader(config: ::Gitlab.config.packages.object_store,
+                                  uploader: ::Packages::PackageFileUploader,
+                                  remote_directory: 'packages',
+                                  **params)
+  end
+
+  def stub_dependency_proxy_object_storage(**params)
+    stub_object_storage_uploader(config: ::Gitlab.config.dependency_proxy.object_store,
+                                  uploader: ::DependencyProxy::FileUploader,
+                                  remote_directory: 'dependency_proxy',
+                                  **params)
+  end
+
+  def stub_object_storage_pseudonymizer
+    stub_object_storage(connection_params: Pseudonymizer::Uploader.object_store_credentials,
+                        remote_directory: Pseudonymizer::Uploader.remote_directory)
+  end
+
   def stub_object_storage_uploader(
         config:,
         uploader:,
@@ -89,8 +108,3 @@ module StubObjectStorage
       EOS
   end
 end
-
-require_relative '../../../ee/spec/support/helpers/ee/stub_object_storage' if
-  Dir.exist?("#{__dir__}/../../../ee")
-
-StubObjectStorage.prepend_if_ee('EE::StubObjectStorage')