Change `Harness::run` to run until no more repaints are requested #13983

Job	Run time
android	25s
cargo-deny aarch64-apple-darwin	40s
cargo-deny aarch64-linux-android	41s
cargo-deny i686-pc-windows-gnu	38s
cargo-deny i686-pc-windows-msvc	38s
cargo-deny i686-unknown-linux-gnu	39s
cargo-deny wasm32-unknown-unknown	37s
cargo-deny x86_64-apple-darwin	39s
cargo-deny x86_64-pc-windows-gnu	38s
cargo-deny x86_64-pc-windows-msvc	39s
cargo-deny x86_64-unknown-linux-gnu	38s
cargo-deny x86_64-unknown-linux-musl	38s
cargo-deny x86_64-unknown-redox	37s
Check wasm32 + wasm-bindgen	2m 26s
Check wasm32+atomics	1m 21s
Format + check + test	2m 36s
ios	27s
Run tests	2m 26s
Check Windows	2m 37s
	20m 0s

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