Rollup merge of #109749 - compiler-errors:new-solver-float-var, r=lcnr

Canonicalize float var as float in new solver

Typo in new canonicalizer -- we should be canonicalizing float vars as `CanonicalTyVarKind::Float`, not `CanonicalTyVarKind::Int`.

Fixes compiler-errors/next-solver-hir-issues#9