fix(kuma-cp): don't fail when 2 headless services pointing to the same service (backport of #7282)

[kumahq]

Automatic cherry-pick of #7282 for branch release-2.0

Generated by action

cherry-picked commit 7f5680d
⚠️ ⚠️ ⚠️ Conflicts happened when cherry-picking! ⚠️ ⚠️ ⚠️

On branch release-2.0
Your branch is up to date with 'origin/release-2.0'.

You are currently cherry-picking commit 7f5680d92.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   pkg/dns/vips/virtual_outbound_view.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   pkg/dns/vips_allocator_test.go