Remove loopy superclass solve mechanism in GHC 9.10

For migration purposes, we re-instated the mechanism which allows GHC to solve a superclass constraint with another superclass constraint in a way which might not terminate at runtime (see MR !9921 (closed)). Whenever this behaviour is relied upon, we get a warning (starting from GHC 9.6), which says that this will stop working in GHC 9.10. This ticket tracks the task of removing this feature in GHC 9.10.

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