build(docs-infra): remove obsolete properties from zipper.json files (#36018)

The `removeSystemJsConfig` and `type` properties (present in some
`zipper.json` files) are now obsolete and are not taken into account by
the example zipper:
- `removeSystemJsConfig` is no longer relevant since most examples have
  been migrated to use the CLI.
- `type` is no longer relevant, because the project type is determined
  based on the `projectType` property in `example-config.json` files.

This commit removes these properties from `zipper.json` files and
updates the `example-zipper` docs to not mention them.

PR Close #36018

aio/content/examples/universal/zipper.json

@@ -1,9 +1,7 @@
 {
-  "files":[
+  "files": [
     "!dist/",
     "!**/*.d.ts",
     "!**/src/**/*.js"
-  ],
-  "removeSystemJsConfig": false,
-  "type": "universal"
+  ]
 }