change client worker tests to be blind to heartbeats
change client worker tests to be blind to heartbeats

jcrist/dask,jayhetee/dask,jcrist/dask,ssanderson/dask,dask/dask,vikhyat/dask,mraspaud/dask,jakirkham/dask,blaze/dask,freeman-lab/dask,vikhyat/dask,simudream/dask,ContinuumIO/dask,cowlicks/dask,mikegraham/dask,wiso/dask,ContinuumIO/dask,blaze/dask,freeman-lab/dask,jayhetee/dask,mrocklin/dask,clarkfitzg/dask,chrisbarber/dask,gameduell/dask,mraspaud/dask,pombredanne/dask,PhE/dask,PhE/dask,clarkfitzg/dask,simudream/dask,wiso/dask,cpcloud/dask,jakirkham/dask,ssanderson/dask,mrocklin/dask,dask/dask,pombredanne/dask