Add a delay between killing teamd processes

[saiarcot895]

What I did

When killing 10 or more teamd processes, add a delay of 0.1 seconds after every 10 kill signals/proceses. This is because in the LAG scale tests (in ecmp/inner_hashing/test_inner_hashing_lag.py in sonic-mgmt), it may create 100 LAGs, and when destroying them all, some of those LAGs may fail to be properly destroyed, leaving some stale port channels around. This seems to be because the netlink socket buffers on which the teamd processes get notifications become full with events of the other port channels/interfaces going down

Why I did it

As a workaround, add some delays in killing the teamd processes, so that the netlink buffers don't become full, causing messages to get dropped.

This delay was randomly chosen, and it seems to work well with 100 LAGs on a KVM. It can probably made to be a bit more aggressive if needed (i.e. maybe 0.05 seconds every 20 processes).

How I verified it

On a KVM testbed with t0-116 topology with a bit more than 100 LAGs, stop teamd using sudo systemctl stop teamd, and verify that all of the LAGs were deleted, and there were no messages from the kernel similar to the following:

Oct 12 21:33:03 vlab-04 kernel: PortChannel41 (unregistering): Failed to send options change via netlink (err -105)
Oct 12 21:33:03 vlab-04 kernel: PortChannel17 (unregistering): Failed to send options change via netlink (err -105)
Oct 12 21:33:03 vlab-04 kernel: PortChannel22: Failed to send options change via netlink (err -105)
Oct 12 21:33:03 vlab-04 kernel: PortChannel22: Failed to send port change of device Ethernet136 via netlink (err -105)
Oct 12 21:33:03 vlab-04 kernel: PortChannel22: Port device Ethernet136 removed
Oct 12 21:33:03 vlab-04 kernel: PortChannel43: Failed to send options change via netlink (err -105)
Oct 12 21:33:03 vlab-04 kernel: PortChannel43: Failed to send port change of device Ethernet174 via netlink (err -105)

Details if related

Partial fix for sonic-net/sonic-buildimage#19310.