run frame-omni-bencher overhead command in CI for all runtimes in the runtime matrix (#7459)

As defined in https://github.com/paritytech/polkadot-sdk/issues/6347, we
want to run the omni-benchers overhead command in the CI to be sure that
it keeps working.

Closes https://github.com/paritytech/polkadot-sdk/issues/6347

.github/workflows/check-frame-omni-bencher.yml

@@ -79,6 +79,7 @@ jobs:
       fail-fast: false # keep running other workflows even if one fails, to see the logs of all possible failures
       matrix:
         runtime: ${{ fromJSON(needs.runtime-matrix.outputs.runtime) }}
+        bench_cmd: ["pallet", "overhead"]
     container:
       image: ${{ needs.preflight.outputs.IMAGE }}
     env:
@@ -89,16 +90,26 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: script
+      - name: script (benchmark ${{ matrix.bench_cmd }})
         id: required
+        shell: bash
         run: |
           RUNTIME_BLOB_NAME=$(echo $PACKAGE_NAME | sed 's/-/_/g').compact.compressed.wasm
           RUNTIME_BLOB_PATH=./target/release/wbuild/$PACKAGE_NAME/$RUNTIME_BLOB_NAME
+          BENCH_CMD=${{ matrix.bench_cmd }}
           forklift cargo build --release --locked -p $PACKAGE_NAME -p frame-omni-bencher --features=${{ matrix.runtime.bench_features }} --quiet
-          echo "Running short benchmarking for PACKAGE_NAME=$PACKAGE_NAME and RUNTIME_BLOB_PATH=$RUNTIME_BLOB_PATH"
+          echo "Running short $BENCH_CMD benchmarking for PACKAGE_NAME=$PACKAGE_NAME and RUNTIME_BLOB_PATH=$RUNTIME_BLOB_PATH"
           ls -lrt $RUNTIME_BLOB_PATH
+          
+          if [[ "$BENCH_CMD" == "pallet" ]]; then
+            cmd="./target/release/frame-omni-bencher v1 benchmark pallet --runtime $RUNTIME_BLOB_PATH --all --steps 2 --repeat 1 $FLAGS"
+          elif [[ "$BENCH_CMD" == "overhead" ]]; then
+            cmd="./target/release/frame-omni-bencher v1 benchmark overhead --runtime $RUNTIME_BLOB_PATH"
+          else
+            echo "Error: Unknown BENCH_CMD value: $BENCH_CMD"
+            exit 1
+          fi
 
-          cmd="./target/release/frame-omni-bencher v1 benchmark pallet --runtime $RUNTIME_BLOB_PATH --all --steps 2 --repeat 1 $FLAGS"
           echo "Running command: $cmd"
           eval "$cmd"
       - name: Stop all workflows if failed