flask_app: delete extra imports

Signed-off-by: binren <zhangbr@elab-plus.com>

flask_app.py

@@ -1,11 +1,7 @@
 from flask import Flask, request
-from mvp import Mvp
 import json
-from test_info import TestInfo
-from tongce import TongCe
 from apscheduler_elab import Config
 from flask_apscheduler import APScheduler
-from email_util import EmailUtil
 import decimal
 from report_push import ReportPush
 from jianye_report import JianYeReport