chore(Data/List/Lemmas): deprecate tail_reverse_eq_reverse_dropLast (#19874)

Makes `tail_reverse_eq_reverse_dropLast` a deprecated alias to [`tail_reverse`](https://github.com/leanprover/lean4/blob/938651121f3d8819109eee75722a1de087feff71/src/Init/Data/List/Lemmas.lean#L2990-L2994), which was added to core in leanprover/lean4#5360.

This duplicated lemma was found by [`tryAtEachStep`](https://github.com/dwrensha/tryAtEachStep).

Author: dwrensha

Mathlib/Data/List/Lemmas.lean

@@ -31,16 +31,7 @@ lemma count_flatMap [BEq β] (l : List α) (f : α → List β) (x : β) :
 
 @[deprecated (since := "2024-08-20")] alias getElem_reverse' := getElem_reverse
 
-theorem tail_reverse_eq_reverse_dropLast (l : List α) :
-    l.reverse.tail = l.dropLast.reverse := by
-  ext i v; by_cases hi : i < l.length - 1
-  · simp only [← drop_one]
-    rw [getElem?_eq_getElem (by simpa), getElem?_eq_getElem (by simpa),
-      ← getElem_drop' _, getElem_reverse, getElem_reverse, getElem_dropLast]
-    · simp [show l.length - 1 - (1 + i) = l.length - 1 - 1 - i by omega]
-    all_goals ((try simp); omega)
-  · rw [getElem?_eq_none, getElem?_eq_none]
-    all_goals (simp; omega)
+@[deprecated (since := "2024-12-10")] alias tail_reverse_eq_reverse_dropLast := tail_reverse
 
 @[deprecated (since := "2024-08-19")] alias nthLe_tail := getElem_tail