[MM-16790] Migrate Plugin.Get to Sync by default (#11581)

* Migrate Plugin.Get to Sync by default

* remove unnecessary else branch

* remove unnecesary blank line

app/plugin_key_value_store.go

@@ -69,19 +69,19 @@ func (a *App) CompareAndSetPluginKey(pluginId string, key string, oldValue, newV
 }
 
 func (a *App) GetPluginKey(pluginId string, key string) ([]byte, *model.AppError) {
-	if result := <-a.Srv.Store.Plugin().Get(pluginId, key); result.Err == nil {
-		return result.Data.(*model.PluginKeyValue).Value, nil
-	} else if result.Err.StatusCode != http.StatusNotFound {
-		mlog.Error("Failed to query plugin key value", mlog.String("plugin_id", pluginId), mlog.String("key", key), mlog.Err(result.Err))
-		return nil, result.Err
+	if kv, err := a.Srv.Store.Plugin().Get(pluginId, key); err == nil {
+		return kv.Value, nil
+	} else if err.StatusCode != http.StatusNotFound {
+		mlog.Error("Failed to query plugin key value", mlog.String("plugin_id", pluginId), mlog.String("key", key), mlog.Err(err))
+		return nil, err
 	}
 
 	// Lookup using the hashed version of the key for keys written prior to v5.6.
-	if result := <-a.Srv.Store.Plugin().Get(pluginId, getKeyHash(key)); result.Err == nil {
-		return result.Data.(*model.PluginKeyValue).Value, nil
-	} else if result.Err.StatusCode != http.StatusNotFound {
-		mlog.Error("Failed to query plugin key value using hashed key", mlog.String("plugin_id", pluginId), mlog.String("key", key), mlog.Err(result.Err))
-		return nil, result.Err
+	if kv, err := a.Srv.Store.Plugin().Get(pluginId, getKeyHash(key)); err == nil {
+		return kv.Value, nil
+	} else if err.StatusCode != http.StatusNotFound {
+		mlog.Error("Failed to query plugin key value using hashed key", mlog.String("plugin_id", pluginId), mlog.String("key", key), mlog.Err(err))
+		return nil, err
 	}
 
 	return nil, nil