Fixed a flaky test in quota tests.
Fixed a flaky test in quota tests.

The `AvailableResourcesAfterRescinding` test became flaky after we
stopped offering unreserved resources beyond quota in
https://reviews.apache.org/r/42835. Hence the allocator offers
rescinded resources to `framework1` if an allocation happens before
the test finishes, which violates the expectation that `framework1`
receives resources only once. Since we do not really care about
allocations in this test but rather about rescinded resources, the
fix is just to ignore subsequent offers to `framework1`.

Review: https://reviews.apache.org/r/42908/

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