Rust

Minor: Make `group_schema` as `PhysicalGroupBy` method #36752

Job	Run time
Check cargo fmt	42s
Check License Header	2m 29s
linux build test	3m 56s
build with wasm-pack	3m 33s
cargo test (macos-aarch64)	11m 4s
Verify MSRV (Min Supported Rust Version)	9m 24s
Verify Vendored Code	52s
cargo test (amd64)	13m 0s
cargo check functions	1m 37s
cargo check no default features	8m 14s
cargo check datafusion	4m 59s
check Cargo.toml formatting	3m 25s
clippy	6m 20s
check configs.md and ***_functions.md is up-to-date	4m 20s
cargo doc	4m 48s
cargo test datafusion-cli (amd64)	4m 46s
cargo test doc (amd64)	18m 11s
cargo examples (amd64)	15m 23s
Run sqllogictest with Postgres runner	4m 59s
verify benchmark results (amd64)	8m 26s
cargo test pyarrow (amd64)	3m 16s
	2h 13m 44s

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