[refurb] Count codepoints not bytes for `slice-to-remove-prefix-or-suffix (FURB188)` #33731

Job	Run time
cargo fmt	16s
Determine changes	9s
python package	1m 14s
pre-commit	31s
mkdocs	2m 30s
cargo test (windows)	7m 13s
cargo clippy	1m 51s
cargo test (linux)	3m 58s
cargo build (msrv)	3m 18s
cargo build (release)	5m 47s
cargo test (wasm)	1m 32s
benchmarks	5m 20s
cargo shear	22s
cargo fuzz	4m 15s
formatter instabilities and black similarity	4m 0s
test scripts	1m 0s
Fuzz the parser	5m 37s
ecosystem	13m 50s
test ruff-lsp	17s
	1h 3m 0s

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