ActivityTool: Use UnrestrictedMethod instead of ad-hoc user for process_timer

This is required cause while running  _activeSense for portal_alarm, we switch
user to nobody so as to use system user, but at the same time in proces_timer
in ActivityTool, we use the user of portal_catalog to invoke the activities.

https://lab.nexedi.com/nexedi/erp5/blob/master/product/ERP5/Document/Alarm.py#L164

The problem comes when someone runs an alarm which create a new portal_catalog,
which might not be having the required permission to invoke all the activites.
So, its better to use unrestrictedMethod or maybe, super_user here.

product/CMFActivity/ActivityTool.py

@@ -54,6 +54,7 @@ from zExceptions import ExceptionFormatter
 from BTrees.OIBTree import OIBTree
 from Zope2 import app
 from Products.ERP5Type.UnrestrictedMethod import PrivilegedUser
+from Products.ERP5Type.UnrestrictedMethod import UnrestrictedMethod
 from zope.site.hooks import setSite
 import transaction
 from App.config import getConfiguration
@@ -993,6 +994,7 @@ class ActivityTool (Folder, UniqueObject):
           LOG('CMFActivity', INFO, "Shutdown: Activities finished.")
 
     security.declareProtected(CMFCorePermissions.ManagePortal, 'process_timer')
+    @UnrestrictedMethod
     def process_timer(self, tick, interval, prev="", next=""):
       """
       Call distribute() if we are the Distributing Node and call tic()
@@ -1011,11 +1013,6 @@ class ActivityTool (Folder, UniqueObject):
           self.setupCurrentSkin(self.REQUEST)
           old_sm = getSecurityManager()
           try:
-            # get owner of portal_catalog, so normally we should be able to
-            # have the permission to invoke all activities
-            user = self.portal_catalog.getWrappedOwner()
-            newSecurityManager(self.REQUEST, user)
-
             currentNode = self.getCurrentNode()
             self.registerNode(currentNode)
             processing_node_list = self.getNodeList(role=ROLE_PROCESSING)