Revert "K2/Java: add private enum constructor for MPP matching"

Review: https://jetbrains.team/p/kt/reviews/13368/timeline

This reverts commit 2cea2b9098.

Motivation:
KT-62961 was fixed independently by two different commits:
- ac3d8ad3ac
- 2cea2b9098

If possible, it's better not to introduce implicit declarations.
That's why it was agreed to keep
ac3d8ad3ac and revert
2cea2b9098

compiler/testData/ir/irText/stubs/javaEnum.__JEnum.fir.ir.txt

@@ -1,6 +1,5 @@
 CLASS IR_EXTERNAL_JAVA_DECLARATION_STUB ENUM_CLASS name:JEnum modality:FINAL visibility:public superTypes:[kotlin.Enum<@[FlexibleNullability] <root>.JEnum?>]
   $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.JEnum
-  CONSTRUCTOR IR_EXTERNAL_JAVA_DECLARATION_STUB visibility:private <> () returnType:<root>.JEnum [primary]
   ENUM_ENTRY IR_EXTERNAL_JAVA_DECLARATION_STUB name:ONE
   ENUM_ENTRY IR_EXTERNAL_JAVA_DECLARATION_STUB name:TWO
   ENUM_ENTRY IR_EXTERNAL_JAVA_DECLARATION_STUB name:THREE