[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/codegen/box/collections/removeAtIntOverrideInJava.kt

@@ -1,5 +1,5 @@
 // TARGET_BACKEND: JVM
-// JVM_ABI_K1_K2_DIFF: KT-57300, KT-63857
+// JVM_ABI_K1_K2_DIFF: KT-63857
 
 // FILE: A.java
 abstract public class A extends B {