[Polly] Cast delinearization terms to matching types (#206711)

#204146 revealed that Polly can call `SCEVDivision::divide` with a
numerator and denominator of different types. I believe such divisions
are not meaningful and should be avoided. As far as I can tell, the root
cause is that `SCEVRemoveMax::rewrite` may collect terms whose types
differ from that of the original expression.

Before this patch, the terms gathered by `SCEVRemoveMax::rewrite` were
used for delinearization as they are. This patch applies
`getTruncateOrSignExtend` to them to matching their types with that of
the original expression.

GitOrigin-RevId: 4538987e5e9241af58246df18e625bfd7809cd04