Issue #2578249 by yched: Some e_r fields get the wrong Selection handler

...Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php

core/modules/entity_reference/entity_reference.module

core/modules/field/field.module

core/modules/field/field.post_update.php

...eld/src/Tests/EntityReference/EntityReferenceItemTest.php

...s/field/src/Tests/Migrate/d6/MigrateFieldInstanceTest.php

.../Tests/Update/EntityReferenceHandlerSettingUpdateTest.php

core/modules/file/src/Tests/FileItemTest.php

core/modules/node/src/Entity/Node.php

.../modules/system/src/Tests/Update/UpdatePostUpdateTest.php

...d/config/install/field.field.node.article.field_image.yml

...ard/config/install/field.field.user.user.user_picture.yml