The `build` and `run` properties in `example-config.json` are only used
in example projects of type `systemjs`. In CLI-type projects, `build`
and `run` are ignored.
PR Close#36015
Also, remove `plnkr.json` for `service-worker-getting-started` guide,
since it is not used and ServiceWorker cannot work correctly in
plnkr/stackblitz anyway (e.g. no build step to re-compute hashes).
A zipper might be useful and can be added in a subsequent PR, but it is
currently broken (e.g. no dependency on `@angular/service-worker`).
PR Close#20165