Fix test TestVSCode_terminatedEvent.py

This test is broken due to the flaky encoding of top-level JSON key 'memory'
When I run locally (linux) the test passed. However, it failed the build bot: https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/48111/
I will find a way to repro before I can actually fix this issue correctly.

https://reviews.llvm.org/D137455