Fixed API tests to pass with agent authentication delay.
Fixed API tests to pass with agent authentication delay.

This changes three tests to advance the clock after instantiating
an agent to allow the agent to authenticate and register.

A much more detailed analysis of this situation exists in MESOS-6803.

reneploetz/mesos,gsantovena/mesos,andschwa/mesos,kaysoky/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,Gilbert88/mesos,yuquanshan/customizedMesos,jpeach/mesos,jpeach/mesos,dforsyth/mesos,andschwa/mesos,dforsyth/mesos,asamerh4/mesos,asamerh4/mesos,abudnik/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,kaysoky/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,jpeach/mesos,abudnik/mesos,neilconway/mesos,Gilbert88/mesos,neilconway/mesos,zmalik/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,dforsyth/mesos,zmalik/mesos,andschwa/mesos,neilconway/mesos,craimbert/mesos,verizonlabs/mesos,gsantovena/mesos,dforsyth/mesos,zmalik/mesos,kaysoky/mesos,Gilbert88/mesos,neilconway/mesos,jpeach/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,zmalik/mesos,abudnik/mesos,asamerh4/mesos,gsantovena/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,verizonlabs/mesos,kaysoky/mesos,verizonlabs/mesos,dforsyth/mesos,kaysoky/mesos,yuquanshan/customizedMesos,andschwa/mesos,chhsia0/mesos,abudnik/mesos,neilconway/mesos,zmalik/mesos,reneploetz/mesos,jpeach/mesos,Gilbert88/mesos,gsantovena/mesos,reneploetz/mesos,craimbert/mesos,kaysoky/mesos,asamerh4/mesos,chhsia0/mesos,verizonlabs/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,dforsyth/mesos,chhsia0/mesos,zmalik/mesos,asamerh4/mesos,yuquanshan/customizedMesos,neilconway/mesos,zmalik/mesos,verizonlabs/mesos,abudnik/mesos,craimbert/mesos,gsantovena/mesos,kaysoky/mesos,asamerh4/mesos,gsantovena/mesos,verizonlabs/mesos,neilconway/mesos,reneploetz/mesos,reneploetz/mesos,chhsia0/mesos,gsantovena/mesos,craimbert/mesos,craimbert/mesos,reneploetz/mesos,jpeach/mesos,abudnik/mesos,Gilbert88/mesos,jpeach/mesos,craimbert/mesos,Gilbert88/mesos,chhsia0/mesos,andschwa/mesos,chhsia0/mesos,Gilbert88/mesos,andschwa/mesos,abudnik/mesos