[llvm] [Github] Force premerge to run on US West cluster (PR #161535)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/161535

To debug why the US West cluster is not getting any jobs assigned.

DO NOT MERGE.

>From f05413e02ab4a1cc4e7a721dd1efd532b247c25f Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Wed, 1 Oct 2025 15:10:51 +0000
Subject: [PATCH] [Github] Force premerge to run on US West cluster

To debug why the US West cluster is not getting any jobs assigned.

DO NOT MERGE.
---
 .github/workflows/premerge.yaml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/premerge.yaml b/.github/workflows/premerge.yaml
index a9c107e4a5f08..542466a43796b 100644
--- a/.github/workflows/premerge.yaml
+++ b/.github/workflows/premerge.yaml
@@ -28,7 +28,8 @@ jobs:
     if: >-
         github.repository_owner == 'llvm' &&
         (github.event_name != 'pull_request' || github.event.action != 'closed')
-    runs-on: llvm-premerge-linux-runners
+    runs-on:
+      group: llvm-premerge-cluster-us-west
     steps:
       - name: Checkout LLVM
         uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0