[systemd] disable default systemd udev rules for interfaces

[stepanblyschak]

Why I did it

Fix #7364

99-default.link - was always in SONiC, but previous systemd (<247) had an issue and it did not work due to issue systemd/systemd#3374. Now systemd 247 works.

However, such policy overrides teamd provided mac address which causes teamd netdev to use a random mac
address. Therefore, needs to be disabled.

How I did it

Disable default systemd udev rules for interfaces.

How to verify it

Execute #7364 reproduction script.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012

Description for the changelog

A picture of a cute animal (not mandatory but encouraged)

[lguohan]

1. I update PR 7369, @stepan Blyshchak, can you check if it is accurate?
2. Other than teamd netdev, are you aware of any other netdev is affected?
3. Instead of disable the 99-default.link, is it the same effect if we set the macpolicy=none?

[stepanblyschak]

1. Thanks, it is accurate.
2. I was focued on team devices, but this can happen to phy port netdevs and this was observed by our team
3. Yes, according to what man pages say, although I find it safer to disable it completely to not have to worry about debian upsteam changes in 99-default.link. What do you think?

[lguohan]

since /etc/systemd/network override /usr/lib/systemd/network, i think it is better to provide our own policy explicitly. we can provide a file with mac address policy as none and copy to /etc/systemd/network, it would be better since in the future we may want to customize the other policy as well.