test: fix //test/common/upstream:cluster_manager_impl_test_lib. (#1580)
test: fix //test/common/upstream:cluster_manager_impl_test_lib. (#1580)

Was broken by interaction of #1521 and #1570.
jrajahalme/envoy,rlazarus/envoy,lizan/envoy,envoyproxy/envoy,lizan/envoy,craffert0/envoy,istio/envoy,envoyproxy/envoy,fengli79/envoy,tdmackey/envoy,envoyproxy/envoy-wasm,istio/envoy,craffert0/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy-wasm,tdmackey/envoy,dnoe/envoy,dnoe/envoy,fengli79/envoy,envoyproxy/envoy-wasm,eklitzke/envoy,dnoe/envoy,lizan/envoy,sebrandon1/envoy,envoyproxy/envoy,rlazarus/envoy,lizan/envoy,lizan/envoy,amalgam8/envoy,tdmackey/envoy,envoyproxy/envoy,envoyproxy/envoy,lizan/envoy,envoyproxy/envoy,eklitzke/envoy,jrajahalme/envoy,sebrandon1/envoy,rlazarus/envoy,lyft/envoy,fengli79/envoy,fengli79/envoy,envoyproxy/envoy-wasm,lyft/envoy,jrajahalme/envoy,sebrandon1/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy-wasm,envoyproxy/envoy,eklitzke/envoy,craffert0/envoy,istio/envoy,envoyproxy/envoy,lyft/envoy,amalgam8/envoy,envoyproxy/envoy,istio/envoy,envoyproxy/envoy,craffert0/envoy,sebrandon1/envoy,amalgam8/envoy,dnoe/envoy,lyft/envoy,lyft/envoy,jrajahalme/envoy,istio/envoy,amalgam8/envoy,envoyproxy/envoy-wasm,lyft/envoy,eklitzke/envoy,jrajahalme/envoy,jrajahalme/envoy,dnoe/envoy,eklitzke/envoy,eklitzke/envoy,rlazarus/envoy,istio/envoy,tdmackey/envoy,envoyproxy/envoy,sebrandon1/envoy