Go back to using the storage key 1.0 used for group fabric info. (#24163)

https://github.com/project-chip/connectedhomeip/pull/23409 changed the key under
which we store group fabric info, which breaks reception of group messages if a
node updates from before that change to after that change.

We should just keep using the same key name, especially because sharing a single
storage key for all possible fabric lists (groups and whatever else will want to
store lists of fabric indices) does not necessarily make sense.

Fixes https://github.com/project-chip/connectedhomeip/issues/24161