[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/kt48945b.kt

@@ -1,10 +1,9 @@
 // TARGET_BACKEND: JVM
 // JVM_TARGET: 1.8
-// IGNORE_BACKEND_K2: JVM_IR, JS_IR
-// FIR status: different structure of fake overrides. Fixed in the IR fake override builder.
 // IGNORE_BACKEND: ANDROID
 //  ^ NSME: java.util.AbstractMap.remove
 // FULL_JDK
+// JVM_ABI_K1_K2_DIFF: KT-65095
 
 // FILE: kt48945b.kt
 interface MSS : Map<String, String>