refactor: include metric output_batches into BaselineMetrics #2951

Job	Run time
cargo test hash collisions (amd64)	1h 1m 0s
linux build test	4m 31s
Run sqllogictests with the sqlite test suite	1h 5m 48s
cargo test 'extended_tests' (amd64)	29m 47s
	2h 41m 6s

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