Move Regr_* functions to use UDAF #27882

Job	Run time
Check cargo fmt	38s
cargo check	6m 59s
build with wasm-pack	2m 17s
cargo test (macos)	13m 37s
cargo test (macos-aarch64)	10m 15s
Verify Vendored Code	44s
cargo test (win64)	33m 25s
Verify MSRV (Min Supported Rust Version)	6m 40s
cargo test (amd64)	9m 52s
cargo doc	3m 59s
cargo test doc (amd64)	12m 41s
cargo test datafusion-cli (amd64)	3m 37s
cargo examples (amd64)	11m 51s
Run sqllogictest with Postgres runner	3m 27s
verify benchmark results (amd64)	11m 9s
check Cargo.toml formatting	2m 44s
clippy	5m 7s
check configs.md is up-to-date	2m 30s
cargo test hash collisions (amd64)	8m 49s
cargo test pyarrow (amd64)	2m 49s
	2h 33m 10s

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