mlh: swap net-next kernel from K8s 1.16 to 1.23
mlh: swap net-next kernel from K8s 1.16 to 1.23

As discussed in community meeting, we are swapping the net-next kernel
to run on the latest supported K8s version rather than the oldest
supported one.

Rationale:

- Will allow elimination of duplicate and redundant tests.
- Currently IPv6 services are manually provisioned.
- New feature developments often need latest kernel as kernel changes are needed.

This change is only made on master, and is not backported to stable
branches (not even 1.11).

The Jenkins triggers and Cilium CI Matrix have been updated accordingly:
https://docs.google.com/spreadsheets/d/1TThkqvVZxaqLR-Ela4ZrcJ0lrTJByCqrbdCjnI32_X0/edit#gid=0

Suggested-by: Martynas Pumputis <6b0d31c0d563223024da45691584643ac78c96e8@lambda.lt>
Signed-off-by: Nicolas Busseneau <418d940643b1975d62234ee01246ad4b58904184@isovalent.com>

michi-covalent/cilium,cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium