8 string references to default_plugin_manager in Zircon Profile 8.0

ckeditor.services.yml in core/modules/ckeditor/ckeditor.services.yml

core/modules/ckeditor/ckeditor.services.yml

core.services.yml in core/core.services.yml

core/core.services.yml

editor.services.yml in core/modules/editor/editor.services.yml

core/modules/editor/editor.services.yml

filter.services.yml in core/modules/filter/filter.services.yml

core/modules/filter/filter.services.yml

image.services.yml in core/modules/image/image.services.yml

core/modules/image/image.services.yml

quickedit.services.yml in core/modules/quickedit/quickedit.services.yml

core/modules/quickedit/quickedit.services.yml

search.services.yml in core/modules/search/search.services.yml

core/modules/search/search.services.yml

tour.services.yml in core/modules/tour/tour.services.yml

core/modules/tour/tour.services.yml