Update git submodules

* Update docs/submodules/bottlenecks from branch 'master'
  - Delete testcase of rubbos and vstf.

    JIRA:BOTTLENECK-167

    This patch will delete vstf and rubbos testcase code.
    Include some testcase config file,
    if there will be someone who want to use this testcase
    maybe B or C version code will contain those testcase.
    if you use the D version code to run this two testcase
    we will info you that:
        Rubbos testsuite is not updating anymore.
        This entrance for running Rubbos within Bottlenecks is no longer supported.

    Change-Id: I04e4042ff3998b3696df2ed47a9ffab6f1620ec3
    Signed-off-by: liyin <liyin11@huawei.com>

diff --git a/docs/submodules/bottlenecks b/docs/submodules/bottlenecks
index 2d9642a..6a82571 160000 (submodule)
--- a/docs/submodules/bottlenecks
+++ b/docs/submodules/bottlenecks
@@ -1 +1 @@
-Subproject commit 2d9642a33a6a58f53aceba4ff3d6242f191f25f0
+Subproject commit 6a8257127b3dce1f18a650afe6921a34b6c6f5b8