Add `ProofSizeExt` to benchmarks #5198

Job	Run time
set-image	10s
check-runtime-migration (asset-hub-westend)	5m 34s
check-runtime-migration (asset-hub-rococo)	1h 0m 0s
check-runtime-migration (bridge-hub-westend)	3m 41s
check-runtime-migration (bridge-hub-rococo)	3m 53s
check-runtime-migration (contracts-rococo)	8m 24s
check-runtime-migration (collectives-westend)	3m 44s
check-runtime-migration (coretime-rococo)	3m 57s
	1h 29m 23s

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