Tests

Parallel compactions for Leveled compaction #432

Job	Run time
test (stable, ubuntu-latest)	2m 32s
cross (aarch64-unknown-linux-gnu)	2m 36s
test (stable, windows-latest)	5m 11s
cross (aarch64-unknown-linux-musl)	2m 49s
test (stable, macos-latest)	2m 42s
cross (i686-unknown-linux-gnu)	2m 4s
test (1.74.0, ubuntu-latest)	2m 18s
cross (powerpc64-unknown-linux-gnu)	2m 41s
test (1.74.0, windows-latest)	4m 3s
cross (riscv64gc-unknown-linux-gnu)	2m 25s
test (1.74.0, macos-latest)	2m 26s
	31m 47s

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