FIR: Rework loading overrides of special built-in methods from Java

Some of the changed data is correct, but some diagnostics are incorrect
Corner cases like having both contains(Object) and contains(String)
within implementation of Collection<String> is not supported

compiler/testData/diagnostics/tests/j+k/collectionOverrides/collectionStringImpl.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // FILE: CollectionStringImpl.java
 
 import java.util.Collection;