JVM, JVM_IR: no nullability annotations on private and synthetic methods

NB it looks like it doesn't cover all cases, e.g., some synthetic
methods generated for suspend functions.

compiler/testData/codegen/bytecodeListing/inlineClasses/computablePropertiesInsideInlineClass.txt

@@ -2,7 +2,7 @@
 public final class Foo {
     private final field x: int
     private synthetic method <init>(p0: int): void
-    public synthetic final static @org.jetbrains.annotations.NotNull method box-impl(p0: int): Foo
+    public synthetic final static method box-impl(p0: int): Foo
     public static method constructor-impl(p0: int): int
     public method equals(p0: java.lang.Object): boolean
     public static method equals-impl(p0: int, @org.jetbrains.annotations.Nullable p1: java.lang.Object): boolean