Improve unparser MySQL compatibility #29677

Job	Run time
cargo test (macos)	8m 56s
cargo check	4m 55s
Check cargo fmt	45s
build with wasm-pack	2m 1s
cargo test (macos-aarch64)	10m 47s
Verify MSRV (Min Supported Rust Version)	6m 30s
Verify Vendored Code	43s
cargo test (win64)	42m 36s
cargo examples (amd64)	12m 12s
cargo test datafusion-cli (amd64)	3m 51s
clippy	5m 12s
cargo test hash collisions (amd64)	8m 46s
cargo doc	3m 36s
cargo test (amd64)	9m 27s
cargo test doc (amd64)	14m 20s
Run sqllogictest with Postgres runner	3m 13s
cargo test pyarrow (amd64)	3m 1s
verify benchmark results (amd64)	10m 50s
check Cargo.toml formatting	2m 44s
check configs.md is up-to-date	2m 25s
	2h 36m 50s

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