[LSRA][RyuJIT] Spill single-def vars at def, if def weight is lower than use(s) weight

[CarolEidt]

This is related to #6825
category:cq
theme:register-allocator
skill-level:expert
cost:large

[pgavlin]

Should this be "if the weight of the def is lower than the weight of the use"?

[CarolEidt]

@pgavlin - Yes, thanks.

[kunalspathak]

This is mostly fixed by #54345.