Remove Phoenix cpu from bench matrix

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sbryngelson

.github/workflows/bench.yml

@@ -37,14 +37,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - cluster: phoenix
-            name: Georgia Tech | Phoenix (NVHPC)
-            group: phoenix
-            labels: gt
-            flag: p
-            device: cpu
-            interface: none
-            build_script: ""
           - cluster: phoenix
             name: Georgia Tech | Phoenix (NVHPC)
             group: phoenix