6 files declare their use of LayoutBuilderContextTrait in Drupal 9

ChooseBlockController.php in core/modules/layout_builder/src/Controller/ChooseBlockController.php

ChooseSectionController.php in core/modules/layout_builder/src/Controller/ChooseSectionController.php

ConfigureBlockFormBase.php in core/modules/layout_builder/src/Form/ConfigureBlockFormBase.php

ConfigureSectionForm.php in core/modules/layout_builder/src/Form/ConfigureSectionForm.php

LayoutBuilder.php in core/modules/layout_builder/src/Element/LayoutBuilder.php

MoveBlockForm.php in core/modules/layout_builder/src/Form/MoveBlockForm.php