[FIR] ConeAttributes: fix plus method

The 'plus' method was actually creating a new 'ConeAttributes' with
only one new attribute due to a typo inside 'buildList'

^KT-60451
^KT-60504

compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeAttributes.kt

@@ -96,9 +96,10 @@ class ConeAttributes private constructor(attributes: List<ConeAttribute<*>>) : A
         if (attribute in this) return this
         if (isEmpty()) return predefinedAttributes[attribute] ?: ConeAttributes(attribute)
         val newAttributes = buildList {
-            addAll(this)
+            addAll(arrayMap)
             add(attribute)
         }
+
         return ConeAttributes(newAttributes)
     }