Use opt-level=3 for code size CI job for consistency with Cargo's default release flags.

Author: detly

.github/actions/build-with-patched-std/action.yml

@@ -26,7 +26,7 @@ runs:
     - shell: bash
       id: measure
       env:
-        RUSTC_FLAGS: -Copt-level=s -Cstrip=symbols
+        RUSTC_FLAGS: -Copt-level=3 -Cstrip=symbols
         RUSTC_BUILD_DIR: build/x86_64-unknown-linux-gnu
       working-directory: ${{ inputs.rustc-dir }}
       run: |