selftests: forwarding: vxlan_bridge_1q_mc_ul: Drop useless sleeping

selftests: forwarding: vxlan_bridge_1q_mc_ul: Drop useless sleeping

After fixing traffic matching in the previous patch, the test does not need
to use the sleep anymore. So drop vx_wait() altogether, migrate all callers
of vx{10,20}_create_wait() to the corresponding _create(), and drop the now
unused _create_wait() helpers.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/eabfe4fa12ae788cf3b8c5c876a989de81dfc3d3.1765289566.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>