Update git submodules

* Update docs/submodules/policy/engine.git from branch 'casablanca'
  to e1b6c5ee7c5a5ecf5c985c5d124a315f99956199
  - Upgrade elasticsearch 6.4.3

    Unable to cherry-pick, so making a new review. And
    need to upgrade the version.

    This upgrade fixes a few security issues as described in the JIRA.

    Issue-ID: POLICY-1538
    Change-Id: I467acbb1dce1a922b13a521e9dd40477c012b409
    Signed-off-by: Pamela Dragosh <pdragosh@research.att.com>

diff --git a/docs/submodules/policy/engine.git b/docs/submodules/policy/engine.git
index 30d6815..e1b6c5e 160000 (submodule)
--- a/docs/submodules/policy/engine.git
+++ b/docs/submodules/policy/engine.git
@@ -1 +1 @@
-Subproject commit 30d6815613ee8fc5c9ae838c525313f25ea4ba50
+Subproject commit e1b6c5ee7c5a5ecf5c985c5d124a315f99956199