refactor: simplify synthetic task creation with UserCacheConfig helpers #352

Job	Run time
Test (ubuntu-latest, x86_64-unknown-linux-gnu)	2m 12s
Test (namespace-profile-mac-default, aarch64-apple-darwin)	48s
Test (namespace-profile-mac-default, x86_64-apple-darwin)	2m 23s
Lint	1m 35s
Test (windows-latest, x86_64-pc-windows-msvc)	4m 4s
done	3s
	11m 5s

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