Replace deprecated benchmarking mode (#17222)

## Summary

Minor, noticed this with #17221. CodSpeed has deprecated
`instrumentation` and replaced it with `simulation`, which has the same
meaning:

https://codspeed.io/docs/instruments/cpu/overview#legacy-terminology

## Test Plan

No functional changes.

---------

Signed-off-by: William Woodruff <william@astral.sh>

.github/workflows/ci.yml

@@ -2957,8 +2957,8 @@ jobs:
           mode: walltime
           token: ${{ secrets.CODSPEED_TOKEN }}
 
-  benchmarks-instrumented:
-    name: "benchmarks | instrumented"
+  benchmarks-simulated:
+    name: "benchmarks | simulated"
     runs-on: ubuntu-latest
     needs: determine_changes
     if: ${{ github.repository == 'astral-sh/uv' && !contains(github.event.pull_request.labels.*.name, 'no-test') && (needs.determine_changes.outputs.code == 'true' || github.ref == 'refs/heads/main') }}
@@ -2994,5 +2994,5 @@ jobs:
         uses: CodSpeedHQ/action@346a2d8a8d9d38909abd0bc3d23f773110f076ad # v4.4.1
         with:
           run: cargo codspeed run
-          mode: instrumentation
+          mode: simulation
           token: ${{ secrets.CODSPEED_TOKEN }}