slapos/proxy: setComputerPartitionConnectionXml don't update timestamp

This operation is done by the instance itself, updating the timestamp
here will create an infinity call, where the instance is always edited
and it is forced to run.

  At the ERP5 implementation of slapos master this api don't modify the
timestamp (which is not defined by modification date but by an specific
 workflow.

/cc @jerome

/reviewed-on !151

slapos/proxy/views.py

@@ -244,9 +244,6 @@ def setComputerPartitionConnectionXml():
     requested_by = execute_db('partition',
       'SELECT requested_by FROM %s WHERE reference=? AND computer_reference=?',
       (computer_partition_id, computer_id), one=True)['requested_by']
-    execute_db('partition',
-      "UPDATE %s SET timestamp=? WHERE reference=? AND computer_reference=?",
-      (time.time(), requested_by, computer_id))
   else:
     query = 'UPDATE %s SET connection_xml=? , hosted_by=? WHERE reference=?'
     argument_list = [connection_xml, computer_partition_id, slave_reference]