tests: Remove needless vec #2959

Job	Run time
test (1.81)	1m 40s
test-llvm (14, ubuntu-22.04)	1m 49s
test (stable)	1m 49s
test-llvm (15, ubuntu-22.04)	2m 3s
test (beta)	1m 38s
test-llvm (16)	1m 52s
test (nightly)	2m 5s
test-llvm (17)	1m 49s
test (nightly, macos-latest)	2m 7s
test-llvm (18)	1m 4s
test (nightly, windows-latest)	1m 58s
test-llvm (19)	1m 17s
miri / miri	2m 5s
msrv / prepare	8s
release-dry-run / prepare	9s
tidy / prepare	5s
tidy / tidy	53s
tidy / clippy	24s
tidy / check-external-types	0s
tidy / docs	0s
tidy / deny / deny	12s
msrv / build (ubuntu-latest)	1m 49s
msrv / build (windows-latest)	1m 40s
release-dry-run / build (aarch64-unknown-linux-gnu, ubuntu-20.04)	1m 25s
release-dry-run / build (aarch64-unknown-linux-musl)	1m 11s
release-dry-run / build (aarch64-apple-darwin, macos-13)	1m 45s
release-dry-run / build (x86_64-unknown-linux-gnu, ubuntu-20.04)	1m 4s
release-dry-run / build (x86_64-unknown-linux-musl)	1m 10s
release-dry-run / build (x86_64-apple-darwin, macos-13)	1m 44s
release-dry-run / build (x86_64-pc-windows-msvc, windows-2019)	1m 40s
release-dry-run / build (x86_64-unknown-freebsd)	1m 22s
release-dry-run / build (universal-apple-darwin, macos-13)	1m 45s
	41m 42s

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