Backend ignores NoInits flag, always emit $init$ method on traits

```scala
trait Foo {
  def meth(x: Int): Int
}
```
Compiled with dotty, then decompiled with cfr:
```java
public interface Foo {
    default public void $init$() {
    }

    public int meth(int var1);
}
```
Compiled with Scala 2.12 then decompiled:
```java
public interface Foo {
    public int meth(int var1);
}
```