ci: unpin agent version (#8817)

Author: pkoutsovasilis

.buildkite/bk.integration.pipeline.yml

@@ -12,8 +12,6 @@ env:
   IMAGE_DEBIAN_12: "platform-ingest-elastic-agent-debian-12-1751072471"
   IMAGE_WIN_2022: "platform-ingest-elastic-agent-windows-2022-1751072471"
   IMAGE_WIN_2025: "platform-ingest-elastic-agent-windows-2025-1751072471"
-  # Remove AGENT_VERSION pinning once 8.18.4 DRA and stack are released
-  AGENT_VERSION: "8.18.3-SNAPSHOT"
 
 # This section is used to define the plugins that will be used in the pipeline.
 # See https://buildkite.com/docs/pipelines/integrations/plugins/using#using-yaml-anchors-with-plugins

.buildkite/integration.pipeline.yml

@@ -2,9 +2,6 @@
 
 env:
   VAULT_PATH: "kv/ci-shared/observability-ingest/cloud/gcp"
-  # Remove AGENT_PACKAGE_VERSION and AGENT_VERSION pinning once 8.18.4 DRA and stack are released
-  AGENT_PACKAGE_VERSION: "8.18.3"
-  BEAT_VERSION: "8.18.3"
 
 steps:
   - group: "Integration tests: packaging"

testing/integration/ess/upgrade_broken_package_test.go

@@ -32,7 +32,6 @@ func TestUpgradeBrokenPackageVersion(t *testing.T) {
 		Local: false, // requires Agent installation
 		Sudo:  true,  // requires Agent installation
 	})
-	t.Skip("Skip this test until elastic agent version pinning is removed from Integration test runs on CI")
 
 	ctx, cancel := testcontext.WithDeadline(t, context.Background(), time.Now().Add(10*time.Minute))
 	defer cancel()