Fix broken links in next docs build

- calico: correct relative path (../../) and stale anchor in the maglev
  page's eBPF direct-server-return prerequisite link
- calico-cloud: remove next-only maglev / mark-lb-node cards from the
  networking index (DocCardLink resolves to the released path, where
  these pages don't exist); still reachable via the sidebar
- calico-enterprise: add slug to comms/index so the operations index
  card resolves to a real route

Author: ctauchen

calico-cloud/networking/index.mdx

@@ -28,8 +28,6 @@ The $[prodname] network plugins provide a range of networking options to fit you
   <DocCardLink docId='networking/configuring/workloads-outside-cluster' />
   <DocCardLink docId='networking/configuring/pod-mac-address' />
   <DocCardLink docId='networking/configuring/node-local-dns-cache' />
-  <DocCardLink docId='networking/configuring/add-maglev-load-balancing' />
-  <DocCardLink docId='networking/configuring/mark-lb-node-for-maintenance' />
 </DocCardLinkLayout>
 
 ## IP address management

calico-enterprise/operations/comms/index.mdx

@@ -1,5 +1,6 @@
 ---
 description: Provide custom TLS certificates for Calico components.
+slug: /operations/comms/index
 ---
 
 # Provide TLS certificates for Calico components

calico/networking/configuring/add-maglev-load-balancing.mdx

@@ -26,7 +26,7 @@ Note Maglev load balancing cannot be used with the following:
 
 ## Prerequisites
 
-* Your cluster uses the eBPF data plane with [direct server return mode](../../../operations/ebpf/enabling-ebpf#try-out-direct-server-return-mode).
+* Your cluster uses the eBPF data plane with [direct server return mode](../../operations/ebpf/enabling-ebpf.mdx#enable-direct-server-return-mode).
 * All your nodes are running on Linux.
 * You have a service with a VIP/External-IP, possibly allocated by $[prodname] [LB IPAM](../ipam/service-loadbalancer.mdx), which you are advertising outside of your cluster.