Just like PluginInsert::update_sidechain_name, the name is
implicitly set, using the owning route's name, suffixed with the
[i18n localized] Processor name.
This fixes an issue if a track is renamed and a new track with
the old name is created. This commonly happens during File Import:
For each ImportAsTrack a generic named track (e.g. "Audio") is created
before it is renamed.
Previously this lead to
Failed to register port "Audio 1-trig/midi_in 1", reason is unknown from here
b72268f6e1