webadmin:  Unneeded scroll bar on KeyValueWidget

Change-Id: Ic7f26ace9c783467d8f02d4c9df511b30032bd7e
Bug-Url: https://bugzilla.redhat.com/1116737
Bug-Url: https://bugzilla.redhat.com/1116580
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>