tests: Remove needless vec #2960

Job	Run time
test (1.81)	1m 41s
test-llvm (14, ubuntu-22.04)	2m 6s
test (stable)	1m 43s
test-llvm (15, ubuntu-22.04)	1m 51s
test-llvm (16)	1m 55s
test-llvm (17)	2m 4s
test (beta)	1m 42s
test-llvm (18)	38s
test (nightly)	2m 39s
test-llvm (19)	1m 13s
test (nightly, macos-latest)	3m 37s
msrv / prepare	3s
test (nightly, windows-latest)	4m 45s
release-dry-run / prepare	4s
miri / miri	2m 22s
tidy / prepare	4s
msrv / build (ubuntu-latest)	2m 5s
msrv / build (windows-latest)	3m 20s
release-dry-run / build (aarch64-unknown-linux-gnu, ubuntu-20.04)	1m 31s
release-dry-run / build (aarch64-unknown-linux-musl)	1m 11s
release-dry-run / build (aarch64-apple-darwin, macos-13)	2m 16s
release-dry-run / build (x86_64-unknown-linux-gnu, ubuntu-20.04)	1m 10s
release-dry-run / build (x86_64-unknown-linux-musl)	1m 5s
release-dry-run / build (x86_64-apple-darwin, macos-13)	2m 36s
release-dry-run / build (x86_64-pc-windows-msvc, windows-2019)	4m 31s
release-dry-run / build (x86_64-unknown-freebsd)	1m 18s
release-dry-run / build (universal-apple-darwin, macos-13)	2m 10s
tidy / tidy	59s
tidy / clippy	21s
tidy / check-external-types	0s
tidy / docs	0s
tidy / deny / deny	18s
	53m 18s

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