KT-10460: use unsubstituted descriptors

while comparing overloaded generic functions  for specificity.

compiler/testData/diagnostics/tests/secondaryConstructors/generics2.kt

@@ -6,9 +6,9 @@ class A0<T1, T2> {
 
     constructor(x: T1, y: T2, z: T2): this(x, 1) // ok, delegates to constructor(x: T1, y: Int)
 
-    constructor(x: T1, y: Int): <!NONE_APPLICABLE!>this<!>(x, "")
+    constructor(x: T1, y: Int): this(x, <!TYPE_MISMATCH!>""<!>)
     constructor(x: T1): this(x, 1)
-    constructor(x: T1, y: T2, z: String): <!NONE_APPLICABLE!>this<!>(y, x)
+    constructor(x: T1, y: T2, z: String): this(<!TYPE_MISMATCH!>y<!>, <!TYPE_MISMATCH!>x<!>)
 }
 
 class A1<T1, T2> : B<T1, T2> {