macos_runner_pool has a default value

Author: kukushechkin

.github/workflows/main.yml

@@ -33,7 +33,6 @@ jobs:
     uses: apple/swift-nio/.github/workflows/benchmarks.yml@main
     with:
       benchmark_package_path: "Benchmarks"
-      macos_runner_pool: nightly
 
   construct-integration-test-matrix:
     name: Construct integration test matrix

.github/workflows/pull_request.yml

@@ -34,7 +34,6 @@ jobs:
     uses: apple/swift-nio/.github/workflows/benchmarks.yml@main
     with:
       benchmark_package_path: "Benchmarks"
-      macos_runner_pool: general
 
   cxx-interop:
     name: Cxx interop