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/i18n/zipper.json

@@ -1,11 +1,9 @@
 {
-  "files":[
+  "files": [
     "!dist/",
     "!**/*.d.ts",
     "!src/**/*.js",
     "!doc-files/**/*",
     "**/*.xlf"
-  ],
+  ]
-  "removeSystemJsConfig": true,
-  "type": "i18n"
 }

aio/content/examples/universal/zipper.json

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

aio/tools/example-zipper/README.md

@@ -59,21 +59,6 @@ The problem is that not all examples have a stackblitz but they could offer a zi
 In those cases, you can create a `zipper.json` file with the same syntax. It will be ignored by the
 stackblitz tool.
 
-## Choosing the zip "type"
-
-In both `stackblitz.json` and `zipper.json` you can use two extra properties for the zipper configuration:
-
-```
-{
-  ...
-  "removeSystemJsConfig": true,
-  "type": "testing"
-}
-```
-
-This would generate a zip for a testing application and it will also remove everything related with
-SystemJS.
-
 ## Executing the zip generation
 
 `generateZips.js` will create a zip for each `stackblitz.json`  or `zipper.json` it finds.