[Memory Sheriff] Widen existing suppression

NOTRY=true
TBR=hongbo.min@chromium.org
BUG=268924

Review URL: https://chromiumcodereview.appspot.com/23549026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222131 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/tsan/suppressions.txt

@@ -1125,6 +1125,5 @@
   fun:content::ChildThread::Init
   fun:content::ChildThread::ChildThread
   fun:content::UtilityThreadImpl::UtilityThreadImpl
-  fun:content::UtilityMainThread::InitInternal
 }