RenameIndependentSubregs: Add missing sub-range for new IMPLICIT_DEFs (#89050)

Existing sub-ranges are correctly updated because new IMPLICIT_DEF is
added, but there is missing sub-range for IMPLICIT_DEF itself.
Because of missing sub-range in live-intervals for IMPLICIT_DEF,
register allocator does not know that IMPLICIT_DEF rewrites its
virtual sub-registers and can end up assigning overlapping physical
registers to them.
This results in deleting instructions that were defined by sub-registers
overwritten by IMPLICIT_DEF as they are now dead.