Race condition between teamd and swss service.

[jipanyang]

Description
With the new config mechanism (teammgrd) for teamd, the problem has become more noticeable.

The LAG state in stateDB created by teamsyncd has greater chance of being flushed by swss service.

It is time to add dependency on swss for teamd systemd service.

Steps to reproduce the issue:
1.
config lag/lag member
2.
restart system
3.
check stateDB

Describe the results you received:

root@sonic:/home/admin# teamshow
Flags: A - active, I - inactive, Up - up, Dw - Down, N/A - not available, S - selected, D - deselected
  No.  Team Dev       Protocol     Ports
-----  -------------  -----------  -------------
    1  PortChannel1   LACP(A)(Dw)  Ethernet1(D)
    2  PortChannel2   LACP(A)(Up)  Ethernet2(S)
    3  PortChannel3   LACP(A)(Up)  Ethernet3(S)
    4  PortChannel4   LACP(A)(Dw)  Ethernet4(D)
    5  PortChannel5   LACP(A)(Dw)  Ethernet5(D)
    6  PortChannel6   LACP(A)(Dw)  Ethernet6(D)
    7  PortChannel7   LACP(A)(Dw)  Ethernet7(D)
    8  PortChannel8   LACP(A)(Dw)  Ethernet8(D)
    9  PortChannel9   LACP(A)(Dw)  Ethernet9(D)
   10  PortChannel10  LACP(A)(Dw)  Ethernet10(D)
   11  PortChannel11  LACP(A)(Dw)  Ethernet11(D)
   12  PortChannel12  LACP(A)(Dw)  Ethernet12(D)
   13  PortChannel13  LACP(A)(Dw)  Ethernet13(D)
   14  PortChannel14  LACP(A)(Dw)  Ethernet14(D)
   15  PortChannel15  LACP(A)(Dw)  Ethernet15(D)
   16  PortChannel16  LACP(A)(Dw)  Ethernet16(D)
   17  PortChannel17  LACP(A)(Dw)  Ethernet17(D)
   18  PortChannel18  LACP(A)(Dw)  Ethernet18(D)
   19  PortChannel19  LACP(A)(Dw)  Ethernet19(D)
   20  PortChannel20  LACP(A)(Dw)  Ethernet20(D)

admin@sonic:~$ redis-cli  -n 6
127.0.0.1:6379[6]> keys LAG*
1) "LAG_TABLE|PortChannel9"

[jipanyang]

fixed with #2223