Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Removing the downloaded libvirt-client for the iso build

    JIRA: APEX-529

    Change-Id: I09970847833d3e182a7485c051e2e46d394cfeff
    Signed-off-by: Dan Radez <dradez@redhat.com>
    (cherry picked from commit a9ba058e7711379157ae5f99d08cc793b18f8793)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 205eb09..4eb4cc3 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 205eb09eccd5661dda9ab627c99aab6175783e9b
+Subproject commit 4eb4cc36098057aae95c755ffeb3b2843ddd0435