Update container build

Allow to build migration container also for SLE16.
haveged and ifplugd are packages that no longer exists for SLE16.
However they are also not needed for the SLE15 container use
case. Removing them allows to build for both targets from the
same description

container/sle15/config.kiwi

@@ -34,7 +34,6 @@
         <package name="systemd"/>
         <package name="procps"/>
         <package name="suseconnect-ng"/>
-        <package name="ifplugd"/>
         <package name="iputils"/>
         <package name="tar"/>
         <package name="parted"/>
@@ -59,7 +58,6 @@
         <package name="python3-gcemetadata"/>
         <package name="python3-ec2metadata"/>
         <package name="python3-azuremetadata"/>
-        <package name="haveged"/>
     </packages>
     <packages type="bootstrap">
         <package name="zypper"/>

container/sle16

@@ -0,0 +1 @@
+sle15