[IR] Drop IrSyntheticBodyImpl.toString

It was the only IrElement with custom toString. And there is
a pending MR, which will override toString in IrElementBase, so this one
would be useless.

#KT-65773 In Progress

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSyntheticBodyImpl.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.ir.expressions.impl
@@ -22,8 +11,5 @@ import org.jetbrains.kotlin.ir.expressions.IrSyntheticBodyKind
 class IrSyntheticBodyImpl(
     override val startOffset: Int,
     override val endOffset: Int,
-    override var kind: IrSyntheticBodyKind
-) : IrSyntheticBody() {
-    override fun toString(): String =
-        "IrSyntheticBodyImpl($kind)"
-}
+    override var kind: IrSyntheticBodyKind,
+) : IrSyntheticBody()