Disable flamegraph uploads for walltime benchmarks (#20419)

Author: AlexWaygood

.github/workflows/ci.yaml

@@ -968,6 +968,11 @@ jobs:
 
       - name: "Run benchmarks"
         uses: CodSpeedHQ/action@653fdc30e6c40ffd9739e40c8a0576f4f4523ca1 # v4.0.1
+        env:
+          # enabling walltime flamegraphs adds ~6 minutes to the CI time, and they don't
+          # appear to provide much useful insight for our walltime benchmarks right now
+          # (see https://github.com/astral-sh/ruff/pull/20419)
+          CODSPEED_PERF_ENABLED: false
         with:
           mode: walltime
           run: cargo codspeed run