connectcore-demo-example: preserve "swu" file in update_firmware

Avoid deleting the original "swu" firmware file during the update process,
especially in dual-boot systems.
Previously, the file could be removed from the source path even
in the event of an exception. This change ensures the original file
remains intact regardless of update outcome.

Signed-off-by: Isaac Hermida <isaac.hermida@digi.com>

connectcore-demo-example/demoserver.py

@@ -570,8 +570,6 @@ class RequestHandler(http.server.SimpleHTTPRequestHandler):
                 self.wfile.write(json.dumps({"error": e.stdout}).encode(encoding="utf_8"))
                 fw_process = None
 
-            if is_dual_system() and os.path.exists(path):
-                os.remove(path)
         elif re.search("/ajax/check_firmware_update_running", self.path) is not None:
             # Set the response headers.
             self._set_headers(200)