remove parallelmagic ext from cluster default config

IPython/config/profile/cluster/ipython_config.py

@@ -1,25 +1,19 b''
 c = get_config()
 app = c.InteractiveShellApp
 
 # This can be used at any point in a config file to load a sub config
 # and merge it into the current one.
 load_subconfig('ipython_config.py', profile='default')
 
 lines = """
 from IPython.parallel import *
 """
 
 # You have to make sure that attributes that are containers already
 # exist before using them.  Simple assigning a new list will override
 # all previous values.
 if hasattr(app, 'exec_lines'):
     app.exec_lines.append(lines)
 else:
     app.exec_lines = [lines]
 
-# Load the parallelmagic extension to enable %result, %px, %autopx magics.
-if hasattr(app, 'extensions'):
-    app.extensions.append('parallelmagic')
-else:
-    app.extensions = ['parallelmagic']
-