[MINOR] Remove ScalarFunction from datafusion.proto #10173 #2

Job	Run time
cargo check	3m 47s
Check cargo fmt	1m 9s
build with wasm-pack	3m 0s
cargo test (macos)	19m 17s
Verify MSRV (Min Supported Rust Version)	6m 57s
cargo test (macos-aarch64)	10m 29s
Verify Vendored Code	1m 0s
cargo test (win64)	39m 21s
cargo examples (amd64)	10m 54s
cargo test (amd64)	11m 10s
clippy	5m 1s
cargo test hash collisions (amd64)	10m 40s
cargo doc	4m 26s
cargo test datafusion-cli (amd64)	4m 33s
cargo test doc (amd64)	12m 1s
Run sqllogictest with Postgres runner	4m 19s
cargo test pyarrow (amd64)	2m 50s
verify benchmark results (amd64)	12m 4s
check Cargo.toml formatting	3m 11s
check configs.md is up-to-date	2m 48s
	2h 48m 57s

Provide feedback