Merge branch 'selftests-forwarding-various-fixes'

Ido Schimmel says:

====================
selftests: forwarding: Various fixes

Fix various problems in the forwarding selftests so that they will pass
in the netdev CI instead of being ignored. See commit messages for
details.
====================

Link: https://lore.kernel.org/r/20240208155529.1199729-1-idosch@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>