fix registry TTL.

[aiscrm]

1. When etcd stops, the application cannot stop.
2. Stop consul first, then stop app. Then start consul, the registered service remains in consul registry as an unhealthy status.

[aiscrm]

主要解决两个问题：
1、使用consul作为registry，服务运行期间，如果停止consul，然后再停止服务。这时如果再启动consul，这个服务会永远在consul里不会消失，而且一直是unhealthy的状态。
2、使用etcd作为registry，服务运行期间，停止etcd，然后再停止服务，服务会一直挂在那里停不掉，并且registry心跳一直在报错。此时再启动etcd，服务也还是不会退出，但过一会在etcd中注册的这个服务会不存在了，但访问服务还是没问题的，也就是虽然服务还在，但已经不能被发现了。

[codecov-commenter]

Codecov Report

Merging #1537 (9d97ce8) into main (a996590) will increase coverage by 0.11%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #1537      +/-   ##
==========================================
+ Coverage   68.54%   68.65%   +0.11%     
==========================================
  Files          67       67              
  Lines        3090     3111      +21     
==========================================
+ Hits         2118     2136      +18     
- Misses        792      795       +3     
  Partials      180      180              

Impacted Files	Coverage Δ
app.go	74.73% <0.00%> (-0.80%)	⬇️
transport/http/transport.go	85.18% <0.00%> (ø)
internal/context/context.go	100.00% <0.00%> (+2.98%)	⬆️
config/value.go	68.23% <0.00%> (+3.61%)	⬆️

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