Remove `Rust::make_unique` #8276

Job	Run time
build-and-check-asan	29m 11s
build-and-check-clang-macos	39m 3s
build-and-check-ubuntu-32bit	25m 42s
build-and-check-gcc-5	30m 57s
build-and-check-ubuntu-64bit	25m 14s
build-and-check-ubuntu-64bit-glibcxx	26m 10s
	2h 56m 17s

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