Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - add CheckConnectivity scenario

    Change-Id: I9d246828790467c2a57ba410826ee9751fff89c5
    Signed-off-by: JingLu5 <lvjing5@huawei.com>
    (cherry picked from commit 4712d72a570dc9e2799227d489ee41768881a06d)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 1addec1..0389453 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 1addec17ea56fa077b01c307e64343f69207bfe5
+Subproject commit 0389453486af8b58f77a65a6455068fe95346e47