[LLDB] Remove XFAIL on Windows decorator XPASSes

Following tests are now passing on LLDB AArch64 Windows buildbot:
  lldb-api :: commands/expression/deleting-implicit-copy-constructor/TestDeletingImplicitCopyConstructor.py
  lldb-api :: functionalities/data-formatter/data-formatter-categories/TestDataFormatterCategories.py
  lldb-api :: lang/cpp/constructors/TestCppConstructors.py
  lldb-api :: lang/cpp/namespace/TestNamespace.py
  lldb-api :: lang/cpp/this_class_type_mixing/TestThisClassTypeMixing.py

https://lab.llvm.org/buildbot/#/builders/219/builds/3012

This patch removes XFAIL decorator from all of the above.

Differential Revision: https://reviews.llvm.org/D151268