refactor(@angular/build): optimize vitest in-memory file loading #9270

Job	Run time
lint	12s
build	11s
build-e2e-windows	12s
Browser Compatibility Tests	1s
publish-snapshots	1s
test	1s
e2e-snapshots	1s
e2e	1s
e2e-windows	1s
e2e-package-managers	1s
	42s

Provide feedback