Kibana version: 7.12.1

Elasticsearch version: 7.12.1

Describe the bug:

Email alerts sent by Kibana do not include the space URL on the "View alert in Kibana." link, causing the link not to work when the alert is not created on the default space.

Steps to reproduce:

1. Set the publicBaseUrl property on the kibana.yml file to the mail Kibana Url like "https://elk.company.com"
2. Setup an alert outside the Default space with an Email action.
3. When the email triggers, the URL will be: "https://elk.company.com/app/management/insightsAndAlerting/triggersActions/alert/..."
4. The link won't work as the alert is not on the Default space.

Expected behavior:

The link should contain the space ID on the URL like "https://elk.company.com/s/space1/app/management/insightsAndAlerting/triggersActions/alert/..."