core: mapParams performance improvement

When going through jprofiler snapshots from scale env I noticed that
getDataTimeInstance is taking a lot of time. DateFormat objects is not
used but we create it every time we run mapParams so we can remove it
without any harm.

Change-Id: Ib914112be17442e13148def922a486ccf9c0f63f
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Bug-Url: https://bugzilla.redhat.com/1155146