fix(@angular/cli): handle cases when completion is enabled and running in an older CLI workspace
fix(@angular/cli): handle cases when completion is enabled and running in an older CLI workspace

Previously when having completion enabled and the current workspaces has an older version of the Angular CLI installed in the terminal the below errors is show. This is because the older versions of the CLI do not implement this command. Now we exit gracefully.

```
The specified command ("completion") is invalid. For a list of available options,
run "ng help".

Did you mean "analytics"?
```

Closes #23518

angular/angular-cli,clydin/angular-cli,clydin/angular-cli,angular/angular-cli,clydin/angular-cli,clydin/angular-cli,angular/angular-cli,angular/angular-cli