support stateless connection for bolt

[leizhiyuan]

Your question

in the scene of lvs or vip， we need to keep many connection，and allow disconnect when reach the limit。

https://github.com/alipay/sofa-bolt/wiki/SOFA-Bolt-Handbook#24-%E8%87%AA%E5%8A%A8%E6%96%AD%E8%BF%9E%E4%B8%8E%E9%87%8D%E8%BF%9E

if we only set these options， when the connection we keeped closed， it will fail until next time we reconect

Your scenes

describe your use scenes (why need this feature)

Your advice

describe the advice or solution you'd like

Environment

• SOFARPC version:
• JVM version (e.g. java -version):
• OS version (e.g. uname -a):
• Maven version:
• IDE version:

[leizhiyuan]

https://github.com/alipay/sofa-rpc/pull/509