Issue #3268363 by phenaproxima, tedbow: Load new services after staged changes are applied

package_manager/src/Stage.php

package_manager/tests/fixtures/alpha/1.0.0/composer.json

package_manager/tests/fixtures/alpha/1.1.0/composer.json

...manager/tests/fixtures/updated_module/1.0.0/composer.json

...sts/fixtures/updated_module/1.0.0/updated_module.info.yml

...manager/tests/fixtures/updated_module/1.1.0/composer.json

...fixtures/updated_module/1.1.0/src/PostApplySubscriber.php

...sts/fixtures/updated_module/1.1.0/updated_module.info.yml

...fixtures/updated_module/1.1.0/updated_module.services.yml

...age_manager_test_api/package_manager_test_api.routing.yml

...ts/modules/package_manager_test_api/src/ApiController.php

package_manager/tests/src/Build/PackageUpdateTest.php

package_manager/tests/src/Kernel/StageEventsTest.php

tests/src/Kernel/CronUpdaterTest.php