Remove `r8` permutations of shaders #1845

Job	Run time
cargo check (aarch64-android)	25s
cargo check (msrv) (windows-latest)	1m 29s
cargo check (msrv) (wasm32)	36s
cargo clippy (windows-latest)	2m 14s
cargo check (msrv) (macos-latest)	41s
cargo clippy (macos-latest)	1m 2s
cargo clippy (wasm32)	1m 29s
cargo check (msrv) (ubuntu-latest)	52s
cargo clippy (ubuntu-latest)	1m 26s
cargo doc	28s
formatting	21s
Prime LFS Cache	7s
cargo test (wasm32)	32s
typos	6s
cargo test (windows-latest)	2m 1s
cargo test (macos-latest)	1m 15s
cargo test (ubuntu-latest)	2m 36s
	17m 40s

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