migrate pallet-nomination-pool-benchmarking to benchmarking syntax v2 #12361

Job	Run time
check-dependency-rules	10s
check-fail-ci	16s
check-markdown	19s
check-workspace	23s
preflight / preflight	45s
preflight / ci-versions	1m 23s
check-rust-feature-propagation	2m 21s
check-toml-format	1m 7s
check-umbrella	3m 0s
fmt	1m 16s
test-rust-features	2m 27s
All quick checks passed	1s
	13m 28s

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