[build-script] Don't build benchmarks if just SwiftPM is needed

Author: ahoppen

utils/build-presets.ini

@@ -1468,6 +1468,9 @@ skip-test-xctest
 [preset: mixin_swiftpm_package_macos_platform]
 mixin-preset=mixin_swiftpm_macos_platform
 
+# We don't need to build the benchmark if we just want SwiftPM
+skip-build-benchmarks
+
 # We don't need these platforms. Skip them
 skip-ios
 skip-tvos