Issue #17940: Remove redundant code from _Section.format_help()

Output of func(*args) stored in the next line:

    item_help = join([func(*args) for func, args in self.items])

_Section.items only used by HelpFormatter._add_item() and it looks
like it doesn't have any side effects.

Patch by Yogesh Chaudhari.

Lib/argparse.py

@@ -210,8 +210,6 @@ class HelpFormatter(object):
             if self.parent is not None:
                 self.formatter._indent()
             join = self.formatter._join_parts
-            for func, args in self.items:
-                func(*args)
             item_help = join([func(*args) for func, args in self.items])
             if self.parent is not None:
                 self.formatter._dedent()