Update git submodules

Update git submodules

* Update docs/submodules/clover from branch 'stable/gambia'
  - Merge "Initial commit for Spark to analyze visibility data" into stable/gambia
  - Initial commit for Spark to analyze visibility data

    - Add Apache Spark 2.3 with native Kubernetes support.
    - Runs self contained within K8s cluster in clover-system
    namespace. One container (clover-spark) includes Clover Spark
    JAR artifact. This container interacts with the
    K8s API to spawn a spark-driver pod. This pod in turn spawns executor
    pods to execute Spark jobs.
    - Currently JAR is included in source for convenience and must be
    built with sbt (install sbt and execute sbt package)
    - Includes JAR from DataStax to provide Cassandra connector to analyze
    Cassandra schemas as RDDs (Resilient Distributed Dataset).
    - Includes Redis interface JAR to write analyzed data back to visibility
    (UI, CLI or API).
    - Second container (clover-spark-submit) submits Spark jobs
    continuously to allow Spark to be operated entirely within the cluster.
    - Two Spark jobs (CloverSlow, CloverFast) allows some analytics to be
    provided in real-time and other analytics to be provided over longer
    horizons.
    - Each Spark job spawns two executor pods.
    - Includes yaml manifest to deploy clover-spark-submit with the
    necessary RBAC permissions to interact with the K8s API.
    - Data analyzed includes tracing and metrics schemas obtained by
    clover-collector and written to Cassandra.
    - Docker builds of clover-spark and clover-spark-submit are provided
    and will be pushed as OPNFV DockerHub images in a separate patch.

    Change-Id: I2e92c41fd75d4ebba948c0f8cb60face57005e50
    Signed-off-by: earrage <eddie.arrage@huawei.com>