TMP: revert to webui-ubuntu-arm runner, only use one cc to reduce runs for now

Author: ttytm

.github/workflows/linux.yml

@@ -32,8 +32,8 @@ jobs:
       contents: write
     strategy:
       matrix:
-        os: [ubuntu-latest, buildjet-2vcpu-ubuntu-2204-arm]
-        cc: [clang, gcc]
+        os: [ubuntu-latest, webui-ubuntu-20-04-arm64]
+        cc: [gcc]
       fail-fast: false
     env:
       CC: ${{ matrix.cc }}