Cleanup in TestConcurrentEvents.py
- re-enable tests fixed by Matt's commit this morning (addressed llvm.org/pr16567)
- disabled tests affected by new bug llvm.org/pr16575
- removed some commented out code in inferior



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@185951 91177308-0d34-0410-b5e6-96231b3b80d8