[FIR] Use class scope to get constructors for redeclaration check

#KT-60793 Fixed

compiler/testData/diagnostics/tests/overload/ConstructorVsFunOverload.fir.kt

@@ -1,5 +1,13 @@
 // constructor vs. fun overload
 
+// FILE: J.java
+package constructorVsFun;
+
+public class J {
+    public J(String s) {}
+}
+
+// FILE: test.kt
 package constructorVsFun
 
 class a<!CONFLICTING_OVERLOADS!>()<!> { }
@@ -26,4 +34,6 @@ class Rtyu {
     companion object {
         class ololo() { }
     }
-}
+}
+
+<!CONFLICTING_OVERLOADS!>fun J(s: String)<!> { }