[Flaky test] Error installing endpoint version_conflict_engine_exception causing flakiness in elastic agent tests

[criamico]

Related tickets: elastic/elastic-agent#4883 and elastic/elastic-agent#4158

The following errors appears inconstistently across tests, for instance
https://buildkite.com/elastic/elastic-agent/builds/18059#0195629b-e7ef-4ceb-be3b-057758e26fa6 from elastic/elastic-agent#7179

Error installing fleet package: Error installing endpoint 8.11.0: version_conflict_engine_exception
--
  | Root causes:
  | version_conflict_engine_exception: [data_frame_transform_state_and_stats-endpoint.metadata_united-default-8.11.0]: version conflict, document already exists (current version [1])
  | endpoint_security_test.go:437:
  | Error Trace:	C:/buildkite-agent/builds/bk-agent-prod-gcp-1741116562753477722/elastic/elastic-agent/testing/integration/endpoint_security_test.go:437
  | Error:      	Received unexpected error:
  | error installing fleet package: Error installing endpoint 8.11.0: version_conflict_engine_exception
  | Root causes:
  | version_conflict_engine_exception: [data_frame_transform_state_and_stats-endpoint.metadata_united-default-8.11.0]: version conflict, document already exists (current version [1])

Context

The error in Fleet seems to happen in the transforms install function in

kibana/x-pack/platform/plugins/shared/fleet/server/services/epm/elasticsearch/transform/install.ts

Line 743 in f277497

async function handleTransformInstall({

and it's likely to to be caused by a race condition, as endpoint is installed/uninstalled several times in a short span: see this comment.

There was also a previous attempt to fix this issue:

• discussion
• PR: [Fleet] Fixes Transform's version conflict or not found error to not block install or uninstall of package #177380

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)