luacheck: fix warnings in test/box-tap

Follows up #5457

test/box-tap/feedback_daemon.test.lua

@@ -124,8 +124,8 @@ local fh = fio.open("feedback.json")
 test:ok(fh, "file is created")
 local file_data = fh:read()
 -- Ignore the report time. The data should be equal other than that.
-feedback_save = string.gsub(feedback_save, 'time:(%d+)', 'time:0')
-file_data = string.gsub(feedback_save, 'time:(%d+)', 'time:0')
+feedback_save = string.gsub(feedback_save, '"time":(%d+)', 'time:0')
+file_data = string.gsub(file_data, '"time":(%d+)', 'time:0')
 test:is(file_data, feedback_save, "data is equal")
 fh:close()
 fio.unlink("feedback.json")
@@ -247,7 +247,7 @@ box.space.features_memtx_empty:drop()
 box.space.features_memtx:drop()
 box.space.features_sync:drop()
 
-function check_stats(stat)
+local function check_stats(stat)
     local sub = test:test('feedback operation stats')
     sub:plan(18)
     local box_stat = box.stat()