acceptance: check cluster health more in allocator tests
acceptance: check cluster health more in allocator tests

We now check the cluster health once a minute in allocator tests.
Because we continue on errors (there are many kinds of transient
errors), we need to ensure that no nodes have crashed. If anything
has crashed, we want to abort immediately and download logs.

vaibhavarora/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,glycerine/cockroach,cockroachdb/cockroach,maxlang/cockroach,veteranlu/cockroach,veteranlu/cockroach,arjun4084346/cockroach,petermattis/cockroach,sunya123/cockroach,arjun4084346/cockroach,paperstreet/cockroach,veteranlu/cockroach,vivekmenezes/cockroach,maxlang/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,maxlang/cockroach,maxlang/cockroach,arjun4084346/cockroach,sunya123/cockroach,arjun4084346/cockroach,veteranlu/cockroach,cockroachdb/cockroach,glycerine/cockroach,arjun4084346/cockroach,petermattis/cockroach,glycerine/cockroach,veteranlu/cockroach,arjun4084346/cockroach,glycerine/cockroach,glycerine/cockroach,glycerine/cockroach,arjun4084346/cockroach,petermattis/cockroach,vaibhavarora/cockroach,sunya123/cockroach,paperstreet/cockroach,maxlang/cockroach,maxlang/cockroach,glycerine/cockroach,petermattis/cockroach,maxlang/cockroach,petermattis/cockroach,paperstreet/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,paperstreet/cockroach,glycerine/cockroach,vaibhavarora/cockroach,sunya123/cockroach,vivekmenezes/cockroach,vaibhavarora/cockroach,cockroachdb/cockroach,sunya123/cockroach,paperstreet/cockroach,cockroachdb/cockroach,sunya123/cockroach,vaibhavarora/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,veteranlu/cockroach,maxlang/cockroach,veteranlu/cockroach,cockroachdb/cockroach,petermattis/cockroach,petermattis/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,petermattis/cockroach,vivekmenezes/cockroach,veteranlu/cockroach,sunya123/cockroach,vaibhavarora/cockroach,sunya123/cockroach,cockroachdb/cockroach,arjun4084346/cockroach