cni: Use batch endpoint deletion API in chaining plugin

This commit is to leverage new batch endpoint deletion API instead of
singular endpoint deletion based on ID. The main reason is to provide
backward compatibility on upgrade path.

The current CNI attachment ID requires a valid containerIfName attribute,
however, the endpoints created by old cilium versions (e.g. <1.15) are
not having such details. Any CNI DEL command for these endpoints will
lead to invalid lookup (e.g. DeleteEndpointIDNotFoundCode), and prevent
cleaning up of related resources such as IP addresses.

The impact is only limited to CNI chaining mode, as batch endpoint
deletion API is already used cilium-cni/cmd/cmd.go as part of cilium#27351.

Old endpoint details without (or empty) ContainerIfName

```json
{
  "ID": 423,
  "ContainerName": "",
  "dockerID": "415beb119c4b0910f62634510e921a447893195ebedc30ca0e9cd5bf02569645",
  "DockerNetworkID": "",
  "DockerEndpointID": "",
  "IfName": "eni22524e9e591",
  "IfIndex": 13,
  "ContainerIfName": "",
  "DisableLegacyIdentifiers": false,
  ...
}
```

New endpoint details with valid ContainerIfName (e.g. eth0)

```json
{
  "ID": 3627,
  "ContainerName": "",
  "dockerID": "f89ccf654b878248442981d4c56fe3f50fa127f922b46ee6dccc94ae10e94b79",
  "DockerNetworkID": "",
  "DockerEndpointID": "",
  "IfName": "enia67a2d3c27d",
  "IfIndex": 45,
  "ContainerIfName": "eth0",
  "DisableLegacyIdentifiers": false,
  ...
}
```

Relates: cilium#26894, cilium#27351
Signed-off-by: Tam Mach <tam.mach@cilium.io>

plugins/cilium-cni/chaining/generic-veth/generic-veth.go

@@ -245,8 +245,8 @@ func (f *GenericVethChainer) Add(ctx context.Context, pluginCtx chainingapi.Plug
 }
 
 func (f *GenericVethChainer) Delete(ctx context.Context, pluginCtx chainingapi.PluginContext, delClient *lib.DeletionFallbackClient) (err error) {
-	id := endpointid.NewCNIAttachmentID(pluginCtx.Args.ContainerID, pluginCtx.Args.IfName)
-	if err := delClient.EndpointDelete(id); err != nil {
+	req := &models.EndpointBatchDeleteRequest{ContainerID: pluginCtx.Args.ContainerID}
+	if err := delClient.EndpointDeleteMany(req); err != nil {
 		pluginCtx.Logger.WithError(err).Warning("Errors encountered while deleting endpoint")
 	}
 	return nil