fix rum_clm.py seeking text column name twice (#16624)

Author: dandelin

examples/tensorflow/language-modeling/run_clm.py

@@ -347,10 +347,6 @@ def main():
     column_names = raw_datasets["train"].column_names
     text_column_name = "text" if "text" in column_names else column_names[0]
 
-    # First we tokenize all the texts.
-    column_names = raw_datasets["train"].column_names
-    text_column_name = "text" if "text" in column_names else column_names[0]
-
     def tokenize_function(examples):
         return tokenizer(examples[text_column_name])