fix(es): add delay in TestPasswordFromFile to prevent flakiness

The ES client has background health check goroutines that may continue
running briefly after Close() is called. When the password changes and
a new client is created, the old client is closed but its health check
may still make requests with the old password.

This adds a small delay after the client changes to allow the old
client's background goroutines to fully shut down before the test
proceeds to verify the new password.

Fixes #4743

Signed-off-by: root <root@C20251020184286.local>

Author: root

internal/storage/v1/elasticsearch/factory_test.go

@@ -428,6 +428,12 @@ func runPasswordFromFileTest(t *testing.T) {
 		"expecting es.Client to change for the new password",
 	)
 
+	// Give the old client time to fully shut down its background goroutines
+	// (e.g., health checks) after being closed in onClientPasswordChange.
+	// This prevents flakiness where the old client might still make requests
+	// with the old password after the client has been swapped.
+	time.Sleep(100 * time.Millisecond)
+
 	span2 := &dbmodel.Span{
 		Process: dbmodel.Process{ServiceName: "foo"},
 	}