Update git submodules

* Update docs/submodules/dmaap/datarouter.git from branch 'master'
  to a884c481af24e2405f9389b01842c4671a03a75e
  - Allow storing db.user and db.pass in environment variables

    This patch allows to store and get db.user and db.pass from
    environment variables. This is needed if we want to send those
    variables by helm secrets.

    Issue-ID: OOM-2287
    Signed-off-by: Dominik Mizyn <d.mizyn@samsung.com>
    Change-Id: Ie1736dd4bd89710b441f5cc96dd116bd433ad1b6