Make `Precision<usize>` copy to make it clear clones are not expensive #30461

Job	Run time
cargo test (win64)	42m 42s
cargo check	8m 8s
build with wasm-pack	2m 23s
Check cargo fmt	39s
cargo test (macos-aarch64)	9m 36s
Verify Vendored Code	55s
Verify MSRV (Min Supported Rust Version)	6m 28s
cargo test (macos)	9m 39s
cargo test datafusion-cli (amd64)	4m 1s
cargo examples (amd64)	12m 26s
check Cargo.toml formatting	3m 6s
clippy	5m 14s
cargo test hash collisions (amd64)	13m 49s
cargo doc	3m 51s
cargo test (amd64)	9m 11s
cargo test doc (amd64)	13m 58s
Run sqllogictest with Postgres runner	3m 21s
cargo test pyarrow (amd64)	3m 4s
verify benchmark results (amd64)	10m 54s
check configs.md is up-to-date	2m 38s
	2h 46m 3s

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