perf: cranelift-codegen-meta: use Vec::into_iter in ops_for_type

[dishmaker]

-0.8% less llvm lines

Before:

  Lines                 Copies              Function name
  -----                 ------              -------------
  192891                4360                (TOTAL)
   10042 (5.2%,  5.2%)     1 (0.0%,  0.0%)  cranelift_codegen_meta[b743bf4194d43139]::shared::instructions::define
    3772 (2.0%,  7.2%)     1 (0.0%,  0.0%)  <cranelift_codegen_meta[b743bf4194d43139]::gen_isle::NumericOp>::ops_for_type

After:

  Lines                 Copies              Function name
  -----                 ------              -------------
  191189                4324                (TOTAL)
   10042 (5.3%,  5.3%)     1 (0.0%,  0.0%)  cranelift_codegen_meta[b743bf4194d43139]::shared::instructions::define
    2474 (1.3%,  6.5%)     1 (0.0%,  0.0%)  <cranelift_codegen_meta[b743bf4194d43139]::gen_isle::NumericOp>::ops_for_type

rustc -V
rustc 1.97.1 (8bab26f4f 2026-07-14)