fix(@angular/build): correct Vitest coverage reporting for test files #8579

Job	Run time
build	2m 8s
lint	2m 23s
build-e2e-windows	2m 28s
test	2m 36s
publish-snapshots	2m 34s
Browser Compatibility Tests	2m 33s
e2e-windows (windows-2025, 22, npm, 1)	2m 13s
e2e-windows (windows-2025, 22, npm, 3)	2m 13s
e2e-windows (windows-2025, 22, npm, 5)	2m 13s
e2e-windows (windows-2025, 22, npm, 2)	2m 13s
e2e-windows (windows-2025, 22, npm, 0)	2m 12s
e2e-windows (windows-2025, 22, npm, 4)	2m 13s
e2e-windows (windows-2025, 22, esbuild, 1)	2m 14s
e2e-windows (windows-2025, 22, esbuild, 2)	2m 13s
e2e-windows (windows-2025, 22, esbuild, 0)	2m 12s
e2e-windows (windows-2025, 22, esbuild, 5)	2m 13s
e2e-windows (windows-2025, 22, esbuild, 3)	2m 12s
e2e-windows (windows-2025, 22, esbuild, 4)	2m 11s
e2e-package-managers	1s
e2e-snapshots	1s
e2e	1s
	41m 17s

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