[FAB-14853] make raft IT to wait for OSN

While runing test case in integration tests which involve more than
single Raft node, there is a need to wait until nodes will perform
leader election. Otherwise ordering service might not become available
on time, leading to integration test flakes in CI. This commit changes
e2e integration test which spans 3 Raft node to wait for leader and
ensure ordering service available to serve requests.

Change-Id: Ic7b22c3b6efe192f4cdbd476e7e94c5b5f99ee9d
Signed-off-by: Artem Barger <bartem@il.ibm.com>

Author: C0rWin

integration/e2e/e2e_test.go

@@ -20,7 +20,7 @@ import (
 	"syscall"
 	"time"
 
-	docker "github.com/fsouza/go-dockerclient"
+	"github.com/fsouza/go-dockerclient"
 	"github.com/golang/protobuf/proto"
 	"github.com/hyperledger/fabric-lib-go/healthz"
 	"github.com/hyperledger/fabric/core/aclmgmt/resources"
@@ -212,6 +212,11 @@ var _ = Describe("EndToEnd", func() {
 			blockFile2 := filepath.Join(testDir, "newest_orderer2_block.pb")
 			blockFile3 := filepath.Join(testDir, "newest_orderer3_block.pb")
 
+			By("Ordering service system channel is ready")
+			assertBlockReception(map[string]int{
+				"systemchannel": 0,
+			}, []*nwo.Orderer{orderer1, orderer2, orderer3}, peer, network)
+
 			fetchLatestBlock := func(targetOrderer *nwo.Orderer, blockFile string) {
 				c := commands.ChannelFetch{
 					ChannelID:  "testchannel",