Fix runCheck to ignore stdio of spawned process

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@spotify.com>

.changeset/cli-common-runcheck-stdio-ignore.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli-common': patch
+---
+
+Fixed `runCheck` to ignore stdio of the spawned process, preventing unwanted output from leaking to the terminal.

packages/cli-common/src/run.ts

@@ -211,7 +211,7 @@ export async function runOutput(
  */
 export async function runCheck(args: string[]): Promise<boolean> {
   try {
-    await run(args).waitForExit();
+    await run(args, { stdio: 'ignore' }).waitForExit();
     return true;
   } catch {
     return false;