operator: preallocate cnp list backing array
operator: preallocate cnp list backing array

The number of returned CiliumClusterwideNetworkPolicies is known in
advance, so the preallocation of the backing array will avoid
reallocations after the append.

Signed-off-by: Fabio Falzoi <a3958b26c18ad01cbee6627c44adab1006401257@isovalent.com>

cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium