fix: drop stale Reorder defs re-added during merge

`Reorder.permuteUniv` and `Reorder.isEmpty` (on the pre-leanprover-community#36604 shape of
`Reorder`) were deleted by leanprover-community#36604 when the structure was renamed to
`ArgReorder` and a new `Reorder` wrapper was introduced. They were
accidentally re-added during a merge resolution and reference a
`Reorder` type that is not yet in scope at that point.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: kim-em

Mathlib/Tactic/Translate/Reorder.lean

@@ -59,19 +59,6 @@ open Lean Meta Elab
 /-- A permutation, represented using cycle notation. -/
 abbrev Permutation := List {l : List Nat // 2 ≤ l.length}
 
-/-- Permute a list of either universe levels or universe parameters.
-The current heuristic is to swap the first two universes if the first argument is permuted. -/
-def Reorder.permuteUniv {α} (r : Reorder) (us : List α) : List α :=
-  if r.perm.any (·.1.contains 0) then
-    if let x :: y :: l := us then
-      y :: x :: l
-    else us
-  else us
-
-/-- Return `true` if the reorder doesn't do anything. -/
-def Reorder.isEmpty : Reorder → Bool
-  | { perm, argReorders } => perm.isEmpty && argReorders.isEmpty
-
 namespace Permutation
 
 /-- Permute an array of arguments using the given reorder. -/