Always use `StringViewArray` as output of `substr` #38102

Job	Run time
linux build test	5m 4s
Check License Header	2m 32s
Check cargo fmt	43s
build with wasm-pack	3m 51s
cargo test (macos-aarch64)	15m 26s
Verify MSRV (Min Supported Rust Version)	10m 35s
Verify Vendored Code	55s
cargo check datafusion	5m 43s
cargo check no default features	10m 9s
clippy	8m 31s
check Cargo.toml formatting	3m 28s
check configs.md and ***_functions.md is up-to-date	4m 43s
cargo check functions	2m 24s
cargo test (amd64)	13m 40s
cargo test datafusion-cli (amd64)	5m 54s
cargo test doc (amd64)	19m 57s
cargo doc	5m 57s
cargo examples (amd64)	17m 7s
Run sqllogictest with Postgres runner	5m 29s
cargo test pyarrow (amd64)	3m 23s
verify benchmark results (amd64)	9m 30s
	2h 35m 1s

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