Revert "Centralize the handling of completion for simple argument lists. (#82085)"

This reverts commit 21631494b068d9364b8dc8f18e59adee9131a0a5.

Reverted because of greendragon failure:

******************** TEST 'lldb-api :: functionalities/completion/TestCompletion.py' FAILED ********************
Script:

1 files changed, 12 insertions, 1 deletions

diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
index 52e493b..a1e7e3f 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -403,7 +403,10 @@ public:
                            OptionElementVector &opt_element_vector) override {
     if (request.GetCursorIndex())
       return;
-    CommandObject::HandleArgumentCompletion(request, opt_element_vector);
+
+    lldb_private::CommandCompletions::InvokeCommonCompletionCallbacks(
+        GetCommandInterpreter(), lldb::eThreadIndexCompletion, request,
+        nullptr);
   }
 
   Options *GetOptions() override { return &m_all_options; }
@@ -660,6 +663,14 @@ public:
 
   ~CommandObjectThreadContinue() override = default;
 
+  void
+  HandleArgumentCompletion(CompletionRequest &request,
+                           OptionElementVector &opt_element_vector) override {
+    lldb_private::CommandCompletions::InvokeCommonCompletionCallbacks(
+        GetCommandInterpreter(), lldb::eThreadIndexCompletion, request,
+        nullptr);
+  }
+
   void DoExecute(Args &command, CommandReturnObject &result) override {
     bool synchronous_execution = m_interpreter.GetSynchronous();