…md (#3311)

* [service dependent] describe non-warm-reboot dependency outside systemctl

When dependency was described with systemctl, it will kick in all the time,
including under warm reboot/restart scenarios. This is not what we always
want. For components that are capable of warm reboot/start, they need to
describe dependency in service files.

Signed-off-by: Ying Xie <ying.xie@microsoft.com>

* [service] teamd service should not require swss service

Adding require swss will cause teamd to be killed by systemctl when swss
stops. This is not what we want in warm reboot.

Signed-off-by: Ying Xie <ying.xie@microsoft.com>

* refactoring code

* rename functions to match other functions in the file