[docs] Remove duplicated paragraph in the Testing guide

Author: egorzhdan

docs/Testing.md

@@ -298,14 +298,6 @@ code for the target that is not the build machine:
 
   Add ``REQUIRES: executable_test`` to the test.
 
-* ``%target-run-simple-swift``: build a one-file Swift program and run it on
-  the target machine.
-
-  Use this substitution for executable tests that don't require special
-  compiler arguments.
-
-  Add ``REQUIRES: executable_test`` to the test.
-
 * ``%target-run-stdlib-swift``: like ``%target-run-simple-swift`` with
   ``-parse-stdlib -Xfrontend -disable-access-control``.