Migrate pallet-xcm benchmarks to benchmark v2 syntax #16503

Job	Run time
check-dependency-rules	10s
check-fail-ci	12s
check-markdown	45s
check-readme	3m 6s
check-workspace	12s
preflight / preflight	46s
preflight / ci-versions	55s
check-rust-feature-propagation	1m 58s
fmt	1m 7s
test-rust-features	1m 56s
check-umbrella	2m 17s
check-toml-format	56s
All quick checks passed	1s
	14m 21s

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