MM-57786 Fix Shared Channels plugin api (#26753)

* always ping on plugin registration; SharedChannel.IsValid allow no team for GM

* wait for services to start before ping

* ping plugin remotes synchronously on startup

* remove the waitForInterClusterServices stuff

* don't set remoteid when inviting remote to channel

* Update server/public/model/remote_cluster_test.go

Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

* address review comments

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Ibrahim Serdar Acikgoz <serdaracikgoz86@gmail.com>

server/channels/store/sqlstore/remote_cluster_store.go

@@ -191,6 +191,10 @@ func (s sqlRemoteClusterStore) GetAll(filter model.RemoteClusterQueryFilter) ([]
 		query = query.Where(sq.Eq{"rc.PluginID": filter.PluginID})
 	}
 
+	if filter.OnlyPlugins {
+		query = query.Where(sq.NotEq{"rc.PluginID": ""})
+	}
+
 	if filter.RequireOptions != 0 {
 		query = query.Where(sq.NotEq{fmt.Sprintf("(rc.Options & %d)", filter.RequireOptions): 0})
 	}