policy: Fix test combining of L4 and L7.
policy: Fix test combining of L4 and L7.

Specify slice size as 0 when making it so that it is not full of zero
entries to begin with.

This has no effect on test results, but fixing this reduces confusion
in reading the test output.

Signed-off-by: Jarno Rajahalme <0f1ab0ac7dffd9db21aa539af2fd4bb04abc3ad4@covalent.io>

cilium/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,cilium-team/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,cilium-team/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tgraf/cilium,michi-covalent/cilium,michi-covalent/cilium,tklauser/cilium,cilium/cilium