Revert "Fix a code snippet typo in asyncio docs (python#108427)" (pyt…

…honGH-111271)

This reverts commit 7f31676.

The change resulted in a tautology and should not have been made.  There
may be an opportunity for additional clarity in this section, but this
change wasn't it :)

Ref: python#108427 (comment)

Doc/library/asyncio-task.rst

@@ -592,7 +592,7 @@ Shielding From Cancellation
 
    is equivalent to::
 
-       res = await shield(something())
+       res = await something()
 
    *except* that if the coroutine containing it is cancelled, the
    Task running in ``something()`` is not cancelled.  From the point