fix(@angular/cli): handle cases were having completion enabled but 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 favor the global version if it's greater than the local version of the CLI.

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

Did you mean "analytics"?
```

Closes angular#23518

Author: alan-agius4

packages/angular/cli/lib/init.ts

@@ -79,14 +79,14 @@ let forceExit = false;
     }
 
     const rawCommandName = process.argv[2];
-    // When using the completion command, don't show the warning as otherwise this will break completion.
-    if (isGlobalGreater && rawCommandName !== 'completion') {
-      // If using the update command and the global version is greater, use the newer update command
-      // This allows improvements in update to be used in older versions that do not have bootstrapping
+    if (isGlobalGreater) {
+      // If using the update/completion command and the global version is greater. Use the global version.
+      // - update: This allows improvements in update to be used in older versions that do not have bootstrapping.
+      // - completion: This allows improvements to the completion command and handles the case where older local
+      //   versions of the CLI don't have this command.
       if (
-        rawCommandName === 'update' &&
-        cli.VERSION &&
-        cli.VERSION.major - globalVersion.major <= 1
+        rawCommandName === 'completion' ||
+        (rawCommandName === 'update' && cli.VERSION && cli.VERSION.major - globalVersion.major <= 1)
       ) {
         cli = await import('./cli');
       } else if (await isWarningEnabled('versionMismatch')) {