Allen test race condition in allen_monitor.root

We have frequent intermittent test failures such as this one:

stderr:

SysError in <TFile::TFile>: could not delete /workspace/build/Moore/build/Hlt/Hlt1Conf/qmtest_tmp/allen_monitor.root (errno: 2) No such file or directory

stdout:

ProvideRuntimeOptions                                                    FATAL  Standard std::exception is caught 
ProvideRuntimeOptions                                                    ERROR Failed to open ROOT file allen_monitor.root
HiveDataBrokerSvc                                                        FATAL in sysInitialize(): exception with tag=instantiateAndInitializeAlgorithms is caught
HiveDataBrokerSvc                                                        ERROR instantiateAndInitializeAlgorithms 	 Failed to initialize ProvideRuntimeOptions/ProvideRuntimeOptions	 StatusCode=FAILURE

The problem seems that multiple tests are trying to read/write allen_monitor.root at the same time. Tests should use different files instead.

/cc @acasaisv @raaij @dovombru