[serverless] Update slugs/ids of alerting rule topics

[colleenmcginnis]

Description

@lcawl suggested that we remove "alert" from the slugs and IDs for the alerting rule topics:

• create-anomaly-alert-rule.mdx
  • slug
  • id
  • filename
• create-custom-threshold-alert-rule.mdx
  • slug
  • id
  • filename
• create-elasticsearch-query-alert-rule.mdx
  • filename
• create-error-count-threshold-alert-rule.mdx
  • slug
  • id
  • filename
• create-failed-transaction-rate-threshold-alert-rule.mdx
  • slug
  • id
  • filename
• create-inventory-threshold-alert-rule.mdx
  • slug
  • id
  • filename
• create-latency-threshold-alert-rule.mdx
  • slug
  • id
  • filename
• create-slo-burn-rate-alert-rule.mdx
  • slug
  • id
  • filename

When we do this, we'll need to:

• Update any topics that point to the old slug IDs.
• Check the doclink service and update it was required.
• Implement redirects.

cc @dedemorton

Resources

N/A

Which documentation set does this change impact?

Serverless only

Feature differences

N/A

What release is this request related to?

N/A

Collaboration model

The documentation team

Point of contact.

Main contact: @dedemorton @colleenmcginnis

Stakeholders: @lcawl @elastic/docs-engineering