feat(ec2): Fetch metadata every boot

Following 7f87fa3, we'll setup networking first boot and also respond
to hotplug events, but if network is modified while an instance is
powered off, updates won't be visible to the instance upon next boot.

This commit ensures that on ec2, networking information is fetched
every boot.

Salesforce case #00378972

cloudinit/sources/DataSourceAliYun.py

@@ -23,6 +23,13 @@ class DataSourceAliYun(EC2.DataSourceEc2):
     min_metadata_version = "2016-01-01"
     extended_metadata_versions: List[str] = []
 
+    default_update_events = {
+        EventScope.NETWORK: {
+            EventType.BOOT_NEW_INSTANCE,
+            EventType.HOTPLUG,
+        }
+    }
+
     # Aliyun metadata server security enhanced mode overwrite
     @property
     def imdsv2_token_put_header(self):

cloudinit/sources/DataSourceEc2.py

@@ -108,6 +108,7 @@ class DataSourceEc2(sources.DataSource):
     default_update_events = {
         EventScope.NETWORK: {
             EventType.BOOT_NEW_INSTANCE,
+            EventType.BOOT,
             EventType.HOTPLUG,
         }
     }