Issue #3345881 by tedbow: Remove fake-site fixture for automatic_updates_extensions

...updates_extensions/tests/fixtures/fake-site/composer.json

...updates_extensions/tests/fixtures/fake-site/composer.lock

...s/tests/fixtures/fake-site/vendor/composer/installed.json

...ns/tests/fixtures/fake-site/vendor/composer/installed.php

.../profiles/contrib_profile1/contrib_profile1.info.yml.hide

...tic_updates_test/aaa_automatic_updates_test.info.yml.hide

...eb/projects/aaa_update_test/aaa_update_test.info.yml.hide

...te/web/projects/my_dev_module/my_dev_module.info.yml.hide

.../fake-site/web/projects/my_module/my_module.info.yml.hide

...e-site/web/projects/semver_test/semver_test.info.yml.hide

...s/src/Kernel/AutomaticUpdatesExtensionsKernelTestBase.php