[VOTE][2.0] FLIP-343: Remove parameter in WindowAssigner#getDefaultTrigger()

[Wencong Liu]

Hi dev, 


I'd like to start a vote on FLIP-343.


Discussion thread: 
https://lists.apache.org/thread/zn11f460x70nn7f2ckqph41bvx416wxc
FLIP: https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=263425229


Best regards, 
Wencong Liu