Reference agent issue instead of beats

Author: constanca-m

changelog/fragments/1712583231-leader-election-issue.yaml

@@ -29,4 +29,4 @@ pr: https://github.com/elastic/elastic-agent/pull/4542
 
 # Issue URL; optional; the GitHub issue related to this changeset (either closes or is part of).
 # If not present is automatically filled by the tooling with the issue linked to the PR number.
-issue: https://github.com/elastic/beats/issues/38543
+issue: https://github.com/elastic/elastic-agent/issues/4543