fix(@angular/cli): use recommended TTY check logic

`stdin` can be redirected/piped by various shells but still be interactive.  Node.js recommends only testing `stdout`: https://nodejs.org/api/tty.html#tty_tty

Fixes #14640

Author: clydin

packages/angular/cli/utilities/tty.ts

@@ -11,5 +11,7 @@ export function isTTY(): boolean {
     return !(force === '0' || force.toUpperCase() === 'FALSE');
   }
 
-  return !!process.stdout.isTTY && !!process.stdin.isTTY && !('CI' in process.env);
+  const ci = process.env['CI'];
+
+  return !!process.stdout.isTTY && (!ci || ci === '0' || ci.toUpperCase() === 'FALSE');
 }