refactor all remaining self links in mocks

...ies/metadata-registry/metadata-registry.component.spec.ts

...ries/metadata-registry/metadata-registry.reducers.spec.ts

...istries/metadata-schema/metadata-schema.component.spec.ts

...tion-item-mapper/collection-item-mapper.component.spec.ts

...ollection-item-mapper/collection-item-mapper.component.ts

src/app/core/config/config-response-parsing.service.spec.ts

src/app/core/data/search-response-parsing.service.ts

src/app/core/shared/dspace-object.model.ts

src/app/shared/form/builder/form-builder.service.spec.ts

src/app/shared/mocks/mock-item.ts

src/app/shared/search-form/search-form.component.spec.ts

...ed/search/search-results/search-results.component.spec.ts

...p/submission/sections/form/section-form.component.spec.ts