[LiveIntervals] repairIntervalsInRange: recompute width changes (#78564)

Extend repairIntervalsInRange to completely recompute the interva for a
register if subregister defs exist without precise subrange matches
(LaneMask exactly matching subregister).
This occurs when register sequences are lowered to copies such that the
size of the copies do not match any uses of the subregisters formed
(i.e. during twoaddressinstruction).

The subranges without this change are probably legal, but do not match
those generated by live interval computation. This creates problems with
other code that assumes subranges precisely cover all subregisters
defined, e.g. shrinkToUses().