MINOR: [Dev][JS] Fix lint issues introduced (#13809)

Fixes some trailing whitespace, and removes what _appears_ to be an accidentally committed test file. 

Authored-by: David Li <li.davidm96@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

Author: lidavidm

dev/archery/archery/integration/datagen.py

@@ -1599,7 +1599,7 @@ def _temp_path():
 
         generate_decimal128_case(),
 
-        generate_decimal256_case()        
+        generate_decimal256_case()
         .skip_category('JS'),
 
         generate_datetime_case(),