Duplicate plug/slot names inside the core snap

[pedronis]

this and the difference vs what we see for core-support (which nothing but core and not ubuntu-core or any other snap has a plug for) is caused by the problem/logic explained here:

Auto-connect logic starting from slots of an installed/refreshed snap is naive

When we consider autoconnection candidates we look at both plugs and slots of the refreshed/installed etc snap: starting from its plugs we try to find whether there’s a single slot that would match the plug, this seems to make sense, starting from its slots we also try to find whether there’s single plug that would match the slot, this doesn’t make sense, in general we allow multiple connections to a slot atm.