Split count_distinct.rs into separate modules #22901

Job	Run time
cargo check	2m 44s
cargo test (macos)	33m 9s
Check cargo fmt	45s
build with wasm-pack	2m 11s
Verify MSRV (Min Supported Rust Version)	7m 24s
Verify Vendored Code	58s
cargo test (win64)	41m 47s
cargo examples (amd64)	8m 28s
clippy	4m 54s
cargo test (amd64)	9m 51s
cargo doc	3m 42s
cargo test datafusion-cli (amd64)	3m 27s
cargo test doc (amd64)	10m 43s
cargo test pyarrow (amd64)	2m 30s
Run sqllogictest with Postgres runner	3m 11s
verify benchmark results (amd64)	10m 3s
check Cargo.toml formatting	1m 22s
check configs.md is up-to-date	2m 39s
cargo test hash collisions (amd64)	9m 25s
	2h 39m 13s

Provide feedback