Fix lldb-vscode frame test failure

[yinghuitan]

Summary

Previous patch (https://reviews.llvm.org/D126013) added a new "optimized"
attribute to DAP stack frame this caused some tests, like
lldb-vscode/coreFile/TestVSCode_coreFile.py
to fail because the tests explicitly check for all attributes.

To fix the test failure I decided to remove this attribute.

[clayborg]

Since this "optimized" value isn't part of the actual JSON schema for the stack frames, and since we aren't using it in the IDE, best to remove this until it is either in the protocol definition or used by the IDE.

lldb/tools/lldb-vscode/JSONUtils.cpp

llvm::json::Value CreateStackFrame(lldb::SBFrame &frame) {
   if (func_name)
     frame_name = func_name;
   else
     frame_name = "<unknown>";
   bool is_optimized = frame.GetFunction().GetIsOptimized();
   if (is_optimized)
     frame_name += " [opt]";
   EmplaceSafeString(object, "name", frame_name);
-  object.try_emplace("optimized", is_optimized);
 
   int64_t disasm_line = 0;
   object.try_emplace("source", CreateSource(frame, disasm_line));
 
   auto line_entry = frame.GetLineEntry();
   if (disasm_line > 0) {
     object.try_emplace("line", disasm_line);
   } else {