Skip TestServiceRemoveKeepsIngressNetwork

Ref: moby#39426

This is a common flaky test that I have seen on multiple PRs.  It is not
consistent and should be skipped until it is fixed to be robust.  A
simple fix for the swarm tests is not easy as they all poll and have 1
billion timeouts in all the tests so a skip is valid here.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
(cherry picked from commit b942185)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: crosbymichael

integration/network/service_test.go

@@ -227,6 +227,8 @@ func TestServiceWithPredefinedNetwork(t *testing.T) {
 const ingressNet = "ingress"
 
 func TestServiceRemoveKeepsIngressNetwork(t *testing.T) {
+	t.Skip("FLAKY_TEST")
+
 	skip.If(t, testEnv.OSType == "windows")
 	defer setupTest(t)()
 	d := swarm.NewSwarm(t, testEnv)