Fix C++ version of MonitorStage output issue caused by out of order…

… function calls (#2140)

<img width="532" alt="image" src="https://github.com/user-attachments/assets/39f491c6-4551-44a1-94a9-d3f420cf78e1" />

- [#2121](#2121) ensures the cursor is reset to the last line of output after shutdown by adding `ProgressBarContextManager::mark_pbar_as_completed()`. 
- When executing some of the pipelines, race conditions may cause calling `ProgressBarContextManager::display_all()` after `ProgressBarContextManager::mark_pbar_as_completed()`, which intermittently causes the log display issue above - which should has been fixed by this PR.

Closes #2119 

## By Submitting this PR I confirm:
- I am familiar with the [Contributing Guidelines](https://github.com/nv-morpheus/Morpheus/blob/main/docs/source/developer_guide/contributing.md).
- When the PR is ready for review, new or existing tests cover these changes.
- When the PR is ready for review, the documentation is up to date with these changes.

Authors:
  - Yuchen Zhang (https://github.com/yczhang-nv)
  - David Gardner (https://github.com/dagardner-nv)

Approvers:
  - David Gardner (https://github.com/dagardner-nv)
  - Will Killian (https://github.com/willkill07)

URL: #2140

python/morpheus/morpheus/_lib/include/morpheus/controllers/monitor_controller.hpp

@@ -104,6 +104,12 @@ class ProgressBarContextManager
     {
         std::lock_guard<std::mutex> lock(m_mutex);
 
+        // To avoid display_all() being executed after calling mark_pbar_as_completed() in some race conditions
+        if (m_is_completed)
+        {
+            return;
+        }
+
         // A bit of hack here to make the font settings work. Indicators enables the font options only if the bars are
         // output to standard streams (see is_colorized() in <indicators/termcolor.hpp>), but since we are still using
         // the ostream (m_stdout_os) that is connected to the console terminal, the font options should be enabled.
@@ -114,11 +120,11 @@ class ProgressBarContextManager
         {
             pbar->print_progress(true);
             m_stdout_os << termcolor::reset;  // The font option only works for the current bar
-            m_stdout_os << "\n";
+            m_stdout_os << std::endl;
         }
 
         // After each round of display, move cursor up ("\033[A") to the beginning of the first bar
-        m_stdout_os << "\033[" << m_progress_bars.size() << "A";
+        m_stdout_os << "\033[" << m_progress_bars.size() << "A" << std::flush;
     }
 
     void mark_pbar_as_completed(size_t bar_id)