[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/intersectionOverridesIntersection.kt

@@ -0,0 +1,21 @@
+// FIR_IDENTICAL
+
+// inherits accept from FirDeclarationStatusImpl and FirResolvedDeclarationStatus
+class FirResolvedDeclarationStatusImpl : FirDeclarationStatusImpl(), FirResolvedDeclarationStatus
+
+// inherits accept from FirElement and FirDeclarationStatus
+open class FirDeclarationStatusImpl : FirPureAbstractElement(), FirDeclarationStatus
+
+abstract class FirPureAbstractElement : FirElement
+
+interface FirResolvedDeclarationStatus : FirDeclarationStatus {
+    override fun accept() {}
+}
+
+interface FirDeclarationStatus : FirElement {
+    override fun accept() {}
+}
+
+interface FirElement {
+    fun accept() {}
+}