[FIR] Don't remove subsumed members from intersection overrides's overriddens

This fixes a bunch of missing overridden symbols in IR.
This is also required for fixing KT-59921 in the following commit
where we need to keep all overridden symbols of intersection overrides
so that we can enhance them properly.

#KT-57300 Fixed
#KT-57299 Fixed
#KT-59921
#KT-57300
#KT-62788
#KT-64271
#KT-64382

compiler/testData/diagnostics/tests/override/intersectionOfSubstitutedProperties.kt

@@ -0,0 +1,16 @@
+// FIR_IDENTICAL
+
+abstract class C<T, ModelPropertyT : ModelListPropertyCore<T>>() :
+    A<ModelPropertyT, T>(),
+    I<List<T>>
+
+abstract class A<out ModelPropertyT : ModelPropertyCore<*>, T> {
+    abstract val property: ModelPropertyT
+}
+
+interface I<out T> {
+    val property: ModelPropertyCore<out T>
+}
+
+interface ModelListPropertyCore<T> : ModelPropertyCore<List<T>>
+interface ModelPropertyCore<T>