Issue #3248909 by phenaproxima, tedbow: Do not allow destroying a stage during Apply

automatic_updates.services.yml

package_manager/src/Stage.php

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

...er_test_validation/src/EventSubscriber/TestSubscriber.php

...manager/tests/src/Kernel/PackageManagerKernelTestBase.php

package_manager/tests/src/Kernel/StageTest.php

src/Form/UpdateReady.php

src/Form/UpdaterForm.php

src/Updater.php

tests/src/Functional/UpdaterFormTest.php