tc-testing: avoid action cookies with odd length.

Update odd length cookie hexstrings in csum.json, tunnel_key.json and
bpf.json to be even length to comply with check enforced in commit
0149dabf2a1b ("tc: m_actions: check cookie hexstring len") in iproute2.

Signed-off-by: Briana Oursler <briana.oursler@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>