Don't subscribe to Item events to reload model (#2949)

Related to #2584 and
openhab/openhab-core#4466.

This avoids that the global SSE connection is always established, and
therefore reduces problems with the max parallel HTTP connections
limitation. The global SSE connection is now only established if the web
audio sink or the command Item are enabled.

Whilst this change potentially makes the UI not reload the model
automatically on change, practically the now removed mechanism might
haven't been really useful at all because the model is already reloaded
on Main UI start, and if SSE was not connected the moment an Item
changed the mechanism did not trigger.

Signed-off-by: Florian Hotze <dev@florianhotze.com>

bundles/org.openhab.ui/web/src/components/sse-events-mixin.js

@@ -12,11 +12,10 @@ export default {
   },
   methods: {
     startEventSource () {
-      const topicItems = 'openhab/items/*/added,openhab/items/*/removed,openhab/items/*/updated'
       const topicAudio = 'openhab/webaudio/playurl'
       const commandItem = localStorage.getItem('openhab.ui:commandItem')
       const topicCommand = `openhab/items/${commandItem || ''}/command`
-      let topics = topicItems
+      let topics = null
       if (localStorage.getItem('openhab.ui:webaudio.enable') === 'enabled') {
         topics = topicAudio
       }
@@ -40,11 +39,6 @@ export default {
             this.handleCommand(payload.value)
             break
           default:
-            if (event.topic.startsWith('openhab/items/')) {
-              console.info('Item SSE event received, reloading semantic model ...')
-              this.$store.dispatch('loadSemanticModel')
-              break
-            }
             console.warn('Unhandled SSE event: ' + JSON.stringify(event))
         }
       })