As suggested in this thread:
https://github.com/polkadot-fellows/runtimes/pull/87#discussion_r1400237122

We already have the `IsChildSystemParachain`, which may be used at relay
chain, but it can't be used at a parachain level. So let's use
`AllSiblingSystemParachains` for that. I was thinking about
`AllSystemParachains`, but it may cause wrong impression that it can be
used at a relay chain level.

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Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>