build

Add commit backend for tests, fix bug in `MergedTree` #6939

Job	Run time
Check protos	49s
Clippy check	3m 27s
cargo-deny (advisories)	29s
build (ubuntu-latest)	9m 2s
Check that MkDocs can build the docs	24s
cargo-deny (bans licenses sources)	35s
Check formatting	22s
build (macos-13)	5m 48s
build (windows-latest)	11m 29s
build (ubuntu-latest, --all-features)	6m 35s
	39m 0s

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