Avoid duplicate log entries (#6222)

Previously the logger would have two sinks configured (the default + our custom one). This PR clears the default logger before registering our custom one.

Authors:
  - Jim Crist-Harif (https://github.com/jcrist)

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #6222

python/cuml/cuml/internals/logger.pxd

@@ -47,6 +47,7 @@ IF GPUBUILD == 1:
         cdef cppclass sink_vector:
             void push_back(const sink_ptr& sink) except +
             void pop_back() except +
+            void clear()
 
     cdef extern from "cuml/common/logger.hpp" namespace "ML" nogil:
         cdef cppclass logger:

python/cuml/cuml/internals/logger.pyx

@@ -319,5 +319,6 @@ def flush():
 
 
 IF GPUBUILD == 1:
-    # Set callback functions to handle redirected sys.stdout in Python
+    # Clear existing sinks and add a callback sink to redirect to sys.stdout
+    default_logger().sinks().clear()
     default_logger().sinks().push_back(<sink_ptr> make_shared[callback_sink_mt](_log_callback, _log_flush))