selftests: net: Adapt ethtool mq tests to fix in qdisc graft

selftests: net: Adapt ethtool mq tests to fix in qdisc graft

Because of patch[1] the graft behaviour changed

So the command:

tcq replace parent 100:1 handle 204:

Is no longer valid and will not delete 100:4 added by command:

tcq replace parent 100:4 handle 204: pfifo_fast

So to maintain the original behaviour, this patch manually deletes 100:4
and grafts 100:1

Note: This change will also work fine without [1]

[1] https://lore.kernel.org/netdev/20250111151455.75480-1-jhs@mojatatu.com/T/#u

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>