Update git submodules

* Update docs/submodules/yardstick from branch 'stable/gambia'
  - Merge "Revert "Trex KPI are not collected due to rabbitmq user"" into stable/gambia
  - Revert "Trex KPI are not collected due to rabbitmq user"

    This causes the docker-build jobs to fail in the CI.

    This reverts commit ce809669d3051524508edf5a3d69e83dde8a9080.

    Change-Id: Iea66bc92eaee39c5b7427ea55c190f8c0dbf5ad4
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index df0253c..1d7841d 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit df0253cd111e32f42498da6d9d1c3b351a8ce738
+Subproject commit 1d7841d21af77492674bebf5675d6f33017baf9f