[cloud] Default `encrypted` parameter on ec2_ami_copy to False (#22634)

Set encrypted to default False, rather than None

Otherwise you get:

```
Invalid type for parameter Encrypted, value: None, type: <type 'NoneType'>, valid types: <type 'bool'>)
```

lib/ansible/modules/cloud/amazon/ec2_ami_copy.py

@@ -196,7 +196,7 @@ def main():
         source_image_id=dict(required=True),
         name=dict(default='default'),
         description=dict(default=''),
-        encrypted=dict(type='bool', required=False),
+        encrypted=dict(type='bool', default=False, required=False),
         kms_key_id=dict(type='str', required=False),
         wait=dict(type='bool', default=False),
         wait_timeout=dict(default=1200),