Remove the `Vec` representation #731

Job	Run time
loom	30s
minrust	1m 43s
cross (i686-unknown-linux-gnu)	34s
miri	5m 26s
cross (armv7-unknown-linux-gnueabihf)	35s
nightly	1m 6s
cross (powerpc-unknown-linux-gnu)	37s
rustfmt	13s
cross (powerpc64-unknown-linux-gnu)	34s
cross (wasm32-unknown-unknown)	21s
stable (ubuntu-latest)	58s
tsan	1m 32s
stable (macos-latest)	1m 14s
stable (windows-latest)	3m 49s
Publish Documentation	0s
	19m 12s

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