Fix: add cilium remove old resources option

Give users two options: besides skip Cilium, add
`cilium_remove_old_resources`, default is `false`, when set to `true`,
it will remove the content of the old version, but it will cause the
downtime, need to be careful to use.

Signed-off-by: ChengHao Yang <17496418+tico88612@users.noreply.github.com>

roles/network_plugin/cilium/defaults/main.yml

@@ -1,5 +1,8 @@
 ---
 cilium_min_version_required: "1.15"
+
+# remove migrate after 2.29 released
+cilium_remove_old_resources: false
 # Log-level
 cilium_debug: false