Only add the java.hostname on migration if not already present

More recent servers already have java.hostname in rhn.conf... adding it
at migration would add two lines and blow when inspecting the container
later at upgrade time.

mgradm/shared/templates/migrateScriptTemplate.go

@@ -138,7 +138,9 @@ $SSH {{ .SourceFqdn }} sh -c "systemctl list-unit-files | grep hub-xmlrpc-api |
 
 echo "Altering configuration for domain resolution..."
 sed 's/report_db_host = {{ .SourceFqdn }}/report_db_host = localhost/' -i /etc/rhn/rhn.conf;
-sed 's/server\.jabber_server/java\.hostname/' -i /etc/rhn/rhn.conf;
+if ! grep -q '^java.hostname *=' /etc/rhn/rhn.conf; then
+    sed 's/server\.jabber_server/java\.hostname/' -i /etc/rhn/rhn.conf;
+fi
 sed 's/client_use_localhost: false/client_use_localhost: true/' -i /etc/cobbler/settings.yaml;
 
 echo "Altering configuration for container environment..."

uyuni-tools.changes.cbosdo.migration_fqdn_fix

@@ -0,0 +1 @@
+- Only add java.hostname on migrated server if not present