OZG-4995 Rename `keycloak` test file to `user`

...ontainer/organisationseinheit-container.component.spec.ts

...seinheit-form/organisationseinheit-form.component.spec.ts

...ionseinheit-form/organisationseinheit.formservice.spec.ts

...seinheit-list/organisationseinheit-list.component.spec.ts

.../libs/admin-settings/src/lib/user/user.repository.spec.ts

...ent/libs/admin-settings/src/lib/user/user.service.spec.ts

...client/libs/admin-settings/src/lib/user/user.util.spec.ts

alfa-client/libs/admin-settings/test/user/user.ts