Remove XTIMEOUT from TestHelloWorld on linux

I think it was timing out because of the attach deadlocks, which are now fixed. In any case, it
has passed last 200 buildbot runs, so I am enabling it.

llvm-svn: 256748

lldb/packages/Python/lldbsuite/test/dosep.py

@@ -1147,9 +1147,6 @@ def getExpectedTimeouts(platform_name):
     if target.startswith("linux"):
         expected_timeout |= {
             "TestEvents.py",
-
-            # Times out in ~10% of the times on the build bot
-            "TestHelloWorld.py",
             "TestMultithreaded.py",
             "TestRegisters.py",  # ~12/600 dosep runs (build 3120-3122)
             "TestThreadStepOut.py",