Consider different format for resource_weight_events

In scope of #394779 (closed) issue we extended most of system notes to mention also "old" value when the value is removed. For example instead of "Removed health status" we now add note "Removed health status Needs attention".

For weight we can not create a removal note which would contain old weight (before removal). The reason is that weight changes are logged in resource_weight_events and system notes are generated dynamically for these events and resource_weight_events just stores "new" value, so when weight is removed we store something like this:

# select * from resource_weight_events;
 id | user_id | issue_id | weight |          created_at           
----+---------+----------+--------+-------------------------------
  1 |       1 |      496 |        | 2023-04-27 13:51:52.662515+02

If we would need to show also "old" weight in removal notes, we would need to store previous weight in these events first.