[llvm] [Github][libcxx] Move back to main runner set (PR #171771)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/171771

This moves us back to the main runner set so that the next runner set can be used for upgrading again when we want to do that. This also captures the Github Runner version upgrade.

>From 707063b2779fd6d359d3088cf7ae4f88d09c3518 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Thu, 11 Dec 2025 07:30:37 +0000
Subject: [PATCH] [Github][libcxx] Move back to main runner set

This moves us back to the main runner set so that the next runner set
can be used for upgrading again when we want to do that. This also
captures the Github Runner version upgrade.
---
 .github/workflows/libcxx-build-and-test.yaml | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 36b8d13307868..0a8aff0836917 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -36,7 +36,7 @@ concurrency:
 jobs:
   stage1:
     if: github.repository_owner == 'llvm'
-    runs-on: llvm-premerge-libcxx-next-runners
+    runs-on: llvm-premerge-libcxx-runners
     continue-on-error: false
     strategy:
       fail-fast: false
@@ -73,7 +73,7 @@ jobs:
             **/crash_diagnostics/*
   stage2:
     if: github.repository_owner == 'llvm'
-    runs-on: llvm-premerge-libcxx-next-runners
+    runs-on: llvm-premerge-libcxx-runners
     needs: [ stage1 ]
     continue-on-error: false
     strategy:
@@ -148,19 +148,19 @@ jobs:
           'generic-static',
           'bootstrapping-build'
         ]
-        machine: [ 'llvm-premerge-libcxx-next-runners' ]
+        machine: [ 'llvm-premerge-libcxx-runners' ]
         include:
         - config: 'generic-cxx26'
-          machine: llvm-premerge-libcxx-next-runners
+          machine: llvm-premerge-libcxx-runners
         - config: 'generic-asan'
-          machine: llvm-premerge-libcxx-next-runners
+          machine: llvm-premerge-libcxx-runners
         - config: 'generic-tsan'
-          machine: llvm-premerge-libcxx-next-runners
+          machine: llvm-premerge-libcxx-runners
         - config: 'generic-ubsan'
-          machine: llvm-premerge-libcxx-next-runners
+          machine: llvm-premerge-libcxx-runners
         # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
         - config: 'generic-msan'
-          machine: llvm-premerge-libcxx-next-runners
+          machine: llvm-premerge-libcxx-runners
     runs-on: ${{ matrix.machine }}
     steps:
       - uses: actions/checkout at 8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1