acceptance: Fix race in Docker workaround
acceptance: Fix race in Docker workaround

If a deletion of a container issued by a previous test is not applied
atomically prior to its acknowledgment, we could be seeing a failure
to create a container with a name conflict though once we go back and
check, the conflict may have resolved. Fixes #6474.

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