test(healthcheck): fix flaky tests by adding clean up operation in watch_test.go file

[longyue0521]

进入/healthcheck目录

1. 执行go test -race -failfast -timeout=0 -shuffle=on -count=1 .发现测试时而通过时而失败
   
   分析原因——测试之间有数据依赖:
   使用-shuffle=on参数打乱了测试执行顺序——当先执行TestGetWatchers后执行TestWatch则导致TestWatch失败.
2. 执行go test -race -failfast -timeout=0 -shuffle=on -count=100 -run=TestWatch
   
   分析原因——测试不封闭缺少Clean up阶段,所以不能重复运行

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1536955) 85.54052% compared to head (d32b8ae) 85.63361%.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main        #126         +/-   ##
===================================================
+ Coverage   85.54052%   85.63361%   +0.09309%     
===================================================
  Files            188         188                 
  Lines          16114       16114                 
===================================================
+ Hits           13784       13799         +15     
+ Misses          1771        1756         -15     
  Partials         559         559                 

Flag	Coverage Δ
unittests	85.63361% <ø> (+0.09309%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 5 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.