Remove patchesStrategicMerge that is deprecated

[liornoy]

We use patchesStrategicMerge in our kustomization yamls under the config dir, however, since version 5.0.0 this was deprecated and we need to migrate it. See the following warning message:

# Warning: 'patchesStrategicMerge' is deprecated. Please use 'patches' instead. Run 'kustomize edit fix' to update your Kustomization automatically.

[fedepaol]

To be accurate, we don't need to migrate until it's removed and we use a kubectl version that doesn't support it anymore. @liornoy wanna take this?

[liornoy]

yes, with pleasure. and you're right. I confused deprecated with removed.

[liornoy]

see my comment here: https://github.com/metallb/frr-k8s/pull/2#discussion_r1233331925