subsystem benchmarks: add cpu profiling (#2734)

Ready-to-merge version of
https://github.com/paritytech/polkadot-sdk/pull/2601

- Added optional CPU profiling
- Updated instructions how to set up Prometheus, Pyroscope and Graphana
- Added a flamegraph dashboard
<img width="1470" alt="image"
src="https://github.com/paritytech/polkadot-sdk/assets/27277055/c8f3b33d-3c01-4ec0-ac34-72d52325b6e6">

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Co-authored-by: ordian <[email protected]>