Revert "overall_stats: make dual/quad core stats configurable via meunconfig"

This reverts commit bbaa78541e5583035a24c5db2cf1d2ee645721e1.
Revert "overall_stats: add overall stats for all available cores"

This reverts commit b8cb44b48707cee2e8cff8967dfb23eff6b95b1e.