selftests: net-drv: remove the nic_performance and nic_link_layer tests

selftests: net-drv: remove the nic_performance and nic_link_layer tests

Revert fbbf93556f0c ("selftests: nic_performance: Add selftest for performance of NIC driver")
Revert c087dc54394b ("selftests: nic_link_layer: Add selftest case for speed and duplex states")
Revert 6116075e18f7 ("selftests: nic_link_layer: Add link layer selftest for NIC driver")

These tests don't clean up after themselves, don't use the disruptive
annotations, don't get included in make install etc. etc. The tests
were added before we have any "HW" runner, so the issues were missed.
Our CI doesn't have any way of excluding broken tests, remove these
for now to stop the random pollution of results due to broken env.
We can always add them back once / if fixed.

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: David Wei <dw@davidwei.uk>
Link: https://patch.msgid.link/20250507140109.929801-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>