[lldb] Remove another unused CommandReturnObject variable (NFC)

(cherry picked from commit 26c2da5)

Author: JDevlieghere

lldb/source/Interpreter/CommandObject.cpp

@@ -278,7 +278,6 @@ void CommandObject::HandleCompletion(CompletionRequest &request) {
   } else {
     // Can we do anything generic with the options?
     Options *cur_options = GetOptions();
-    CommandReturnObject result(m_interpreter.GetDebugger().GetUseColor());
     OptionElementVector opt_element_vector;
 
     if (cur_options != nullptr) {