MM-12815: Clearly deprecated disused config settings. (#9751)

* MM-12815: Clearly deprecated disused config settings.

* Fix tests.

cmd/mattermost/commands/test.go

@@ -93,7 +93,6 @@ func serverForWebClientTestsCmdF(command *cobra.Command, args []string) error {
 func setupClientTests(cfg *model.Config) {
 	*cfg.TeamSettings.EnableOpenServer = true
 	*cfg.ServiceSettings.EnableCommands = false
-	*cfg.ServiceSettings.EnableOnlyAdminIntegrations = false
 	*cfg.ServiceSettings.EnableCustomEmoji = true
 	cfg.ServiceSettings.EnableIncomingWebhooks = false
 	cfg.ServiceSettings.EnableOutgoingWebhooks = false