Issue #3308886 by tedbow: Consolidate Test fixture logic

..._composer_validator/active/vendor/composer/installed.json

...module_not_installed_stage/vendor/composer/installed.json

...ndency_not_installed_stage/vendor/composer/installed.json

...rofile_not_installed_stage/vendor/composer/installed.json

.../theme_not_installed_stage/vendor/composer/installed.json

...e_release_validator/active/vendor/composer/installed.json

...acy_supported_update_stage/vendor/composer/installed.json

...y_unsupported_update_stage/vendor/composer/installed.json

...ver_supported_update_stage/composer/vendor/installed.json

...r_unsupported_update_stage/vendor/composer/installed.json

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

...ates_extensions/tests/src/Kernel/ExtensionUpdaterTest.php

.../Validator/PackagesInstalledWithComposerValidatorTest.php

...tests/src/Kernel/Validator/UpdateReleaseValidatorTest.php

.../package_manager_bypass/src/BypassedStagerServiceBase.php

package_manager/tests/src/Kernel/ComposerUtilityTest.php

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

package_manager/tests/src/Traits/FixtureUtilityTrait.php

...n/new_project_added/active/vendor/composer/installed.json

...n/new_project_added/staged/vendor/composer/installed.json