e2e: reduce number of stateless nodes in test networks (#7010)

test/e2e/generator/generate.go

@@ -161,7 +161,7 @@ func generateTestnet(r *rand.Rand, opt map[string]interface{}) (e2e.Manifest, er
 		numValidators = 4
 	case "large":
 		// FIXME Networks are kept small since large ones use too much CPU.
-		numSeeds = r.Intn(2)
+		numSeeds = r.Intn(1)
 		numLightClients = r.Intn(2)
 		numValidators = 4 + r.Intn(4)
 		numFulls = r.Intn(4)