Fix staticcheck errors from _test.go files (#18033)

Automatic Merge

store/storetest/plugin_store.go

@@ -1285,7 +1285,6 @@ func testPluginList(t *testing.T, ss store.Store) {
 		pluginId := model.NewId()
 
 		var keys []string
-		var expiredKeys []string
 		now := model.GetMillis()
 		for i := 0; i < 150; i++ {
 			key := model.NewId()
@@ -1311,8 +1310,6 @@ func testPluginList(t *testing.T, ss store.Store) {
 
 			if expireAt == 0 || expireAt > now {
 				keys = append(keys, key)
-			} else {
-				expiredKeys = append(expiredKeys, key)
 			}
 		}
 		sort.Strings(keys)