orchagent would crash, when portsorch failed to remove bridge port

[inspurSDN]

Root cause:
    Failed to remove bridge port becasue reference count is not 0

Solution:
    1. put DEL task into m_toSync, when portsorch failed to remove bridge port
    2. if port was removed from vlan but m_bridge_port_id is not SAI_NULL_OBJECT_ID,
       portsorch will try to remove bridgeport again until reference count is 0

What I did

Why I did it

How I verified it

Details if related

[prsunny]

Please add unit tests