[LLDB][NFC] Fix memory leak in IntstumentationRuntimeTSan.cpp

ConvertToStructuredArray() relies on its caller to deallocate the heap-allocated object pointer it returns. One of its call-sites, in GetRenumberedThreadIds(), fails to deallocate causing a memory/resource leak. Fix the memory leak by converting the return type to shared_ptr, and clean up the rest of the file to use the typedef-ed shared_ptr types for StructuredData for safety and consistency.

Differential Revision: https://reviews.llvm.org/D131900