reproducer for delay in cancellation caused by CoalescePartitionsExec #7

Job	Run time
linux build test	4m 35s
Run sqllogictests with the sqlite test suite	24m 25s
cargo test hash collisions (amd64)	29m 26s
cargo test 'extended_tests' (amd64)	21m 32s
	1h 19m 58s

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