Some tests disable refresh and verify that documents cannot be found without an explicit refresh. With at least one replica and waiting for yellow though, it can happen that we start indexing docs when the replicas are not ready yet, and as soon as they become ready they get refreshed, causing the newly added docs to be unexpectedly found. Solution is to disable replicas for these specific tests.
REST tests get run against either 1 node or multiple nodes. Wait for yellow with replicas>0 is not enough when running against multiple nodes as replicas shard might get initialized during testing, which can cause timing issues.
This change make single shard requests fail when no routing is specified and routing has been configured to be required in the mapping. Thi
Closes#4506