der: rename `OctetStringRefDeriveHack` #2098

Job	Run time
build (stable, thumbv7em-none-eabi)	21s
build (stable, wasm32-unknown-unknown)	20s
build (1.85.0, thumbv7em-none-eabi)	26s
build (1.85.0, wasm32-unknown-unknown)	27s
test (stable)	24s
test (1.85.0)	25s
minimal-versions	-1s
	2m 22s

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