Minor optimisations included.

This alarm is focus on keep only the minimal and usable set of bt5 installed, this helps on quick upgrades.

Relevant upgraders should be reincluded as constraints.

In case catalog and zodb is at a inconsistent state (after a backup restauration for example), this alarm can check if all security uids are well indexed.

Once a interaction is trigger after _setPredecessor don't propagate reindexation to invalidated software Instances.