Update Python tests for lldb-server on Windows

Summary: Thanks to Hui Huang and reviewers for all the help with this patch!

Reviewers: labath, jfb, clayborg

Reviewed By: labath

Subscribers: Hui, clayborg, dexonsmith, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D61687

llvm-svn: 368776