[MM-21572] Disable InstallFromUrl if EnableUploads is false (#13636)

* Disable InstallFromUrl if EnableUploads is false

* Break into 3 seperate lines

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

api4/plugin_test.go

@@ -145,6 +145,9 @@ func TestPlugin(t *testing.T) {
 	_, resp = th.SystemAdminClient.UploadPlugin(bytes.NewReader(tarData))
 	CheckNotImplementedStatus(t, resp)
 
+	_, resp = th.SystemAdminClient.InstallPluginFromUrl(url, false)
+	CheckNotImplementedStatus(t, resp)
+
 	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.PluginSettings.EnableUploads = true })
 	_, resp = th.Client.UploadPlugin(bytes.NewReader(tarData))
 	CheckForbiddenStatus(t, resp)