K2: Refine mapping of primitive arrays to JVM descriptor

Earlier, it wasn't really important but after the previous commit
when JvmMappedScope semantics has been changed, we erroneously
started loading `toCharArray` as a member to String because
its jvmDescriptor was computed to "toCharArray()Lkotlin/CharArray",
while hardcoded information that prevents it from loading expect
"toCharArray()[C" there.

^KT-57694 In progress

compiler/testData/codegen/box/jdk/noStringToCharArray.kt

@@ -0,0 +1,4 @@
+// WITH_STDLIB
+internal val wildcardChars = "OK".toCharArray()
+
+fun box(): String = "${wildcardChars[0]}${wildcardChars[1]}"