chore(tests/lean): fix style and adjust tests

src/frontends/lean/builtin_cmds.cpp

@@ -104,7 +104,6 @@ struct print_axioms_deps {
         if (!m_use_axioms)
             m_ios << "no axioms" << endl;
     }
-
 };
 
 static void print_axioms(parser & p) {

tests/lean/print_ax1.lean.expected.out

@@ -1 +1,2 @@
-no axioms
+quot.sound : ∀ {A : Type} [s : setoid A] {a b : A}, setoid.r a b → quot.mk a = quot.mk b
+propext : ∀ {a b : Prop}, (a ↔ b) → a = b

tests/lean/print_ax2.lean.expected.out

@@ -1,2 +1,4 @@
+quot.sound : ∀ {A : Type} [s : setoid A] {a b : A}, setoid.r a b → quot.mk a = quot.mk b
 em : ∀ (a : Prop), a ∨ ¬a
+propext : ∀ {a b : Prop}, (a ↔ b) → a = b
 strong_indefinite_description : Π {A : Type} (P : A → Prop), nonempty A → { (x : A)| Exists P → P x}