Remove a dead comment in folly/test/SynchronizedTest.cpp

Summary: [Folly] Remove a dead comment in `folly/test/SynchronizedTest.cpp`.

Reviewed By: simpkins

Differential Revision: D3745609

fbshipit-source-id: acdbd3eaa6d947213b72fe13cec0291545a60c87

folly/test/SynchronizedTest.cpp

@@ -189,11 +189,6 @@ class SynchronizedLockTest : public testing::Test {
   }
 };
 
-/**
- * To avoid typing
- */
-// static constexpr auto one_ms = std::chrono::milliseconds(1);
-
 /**
  * Test mutex to help to automate assertions, taken from LockTraitsTest.cpp
  */