The Agent migrate APIs and actions were added to Fleet Server and Elastic Agent in 9.1.0 (see elastic/elastic-agent#8014 and elastic/fleet-server#4786), but the UI was not enabled by default until these were merged:

• PR for 9.3: [Fleet] Remove feature flag and add license gate for Agent migrations kibana#237342
• backport PR for 9.2: [9.2][Fleet] Remove feature flag and add license gate for Agent migrations (#237342) kibana#239556),
  which didn't get the appropriate release note label.

We need to remove the reference to elastic/fleet-server#4786 from the Fleet Server release notes 9.1, and add the feature to the Kibana release notes 9.2 and the Serverless changelog.

cc: @kpollich @Supplementing