Copy URL for Slack Trigger does not work

### Describe the issue

Under Triggers, hover over the Slack icon and press Copy URL.

This should work the same as a Webhook Trigger but copies nothing to the clipboard.

https://github.com/user-attachments/assets/ba839096-0c34-4c45-806f-7648557d2258

```yaml
id: slack_agent
namespace: company.team

triggers:
- id: slack_mention
key: my_key
type: io.kestra.plugin.slack.app.core.Trigger
botToken: "{{ secret('SLACK_BOT_TOKEN') }}"
signingSecret: "{{ secret('SLACK_SIGNING_SECRET') }}"

tasks:
- id: gemini
type: io.kestra.plugin.gemini.TextCompletion
apiKey: "{{ secret('GEMINI_KEY') }}"
model: gemini-2.5-flash
prompt: |
Answer the user in an informal, conversational tone: {{ trigger.body.text }}

- id: respond_to_mention
type: io.kestra.plugin.slack.app.chats.Post
token: "{{ secret('SLACK_BOT_TOKEN') }}"
channel: "{{ trigger.body.channel }}"
messageText: "{{ outputs.gemini['predictions'] | first | jq('.content') | first }}"
timestamp: "{{ trigger.body.ts }}"
```

### Environment

- Kestra Version: 1.3.10 EE

Start by reproducing the issue in the Slack Trigger UI described in the report, hovering over the Slack icon and using Copy URL. Compare its behavior with the Webhook Trigger, then verify that the Slack Trigger copies its URL to the clipboard as expected.

Written by the indexing model from the issue text.