feat: As a user, I want kubernetes service discovery to support more configuration items

Description

Recently, we deployed apisix on different clouds and used the feature of kubernetes service discovery. The problem is that on different clouds, the proxy layer (LB) in front of apiserver has different idle timeouts. However, in apisix's kubernetes service discovery, The time of a watch is fixed, which will cause a problem: when there is no endpoints event in the cluster for a long time, the server will time out instead of the client, and then the service discovery will restart the list-watch after a fixed 40 seconds , so if you can add some configuration items, such as the duration of a watch, retry time or strategy, etc., thank you!