ATR-23624: Check independence of slices (relatively) quickly

We have been suffering from chains being placed in the wrong slices, causing failures only in the ART tests, which run the slice tests separately -- the CI only checks full menu.

This test allows the chains in each slice to be scanned without attempting to configure the sequences, generating dummy chain configs instead, which expedites the check while still running the menu through the standard parsing. Timeout set to 250s compared to ~180s runtime for 14 slices. We could if preferred schedule the slice tests independently.

CI will demonstrate that the check is working because ATR-23797 is needed to move assignment of chain from the UnconventionalTracking slice to the Combined slice.