Test/esti lakectl large upload - #10591

The compatibility job fails in the new test's cleanup, not in the upload. Both subtests of TestLakectlFsUploadLarge hit this at esti/lakectl_test.go:204 (the adapter.Delete call):

operation error S3: DeleteObject, resolve auth scheme: resolve endpoint: endpoint rule error, Invalid region: region was not a valid DNS name.

That is the AWS SDK v2 error for an empty region. The ESTI S3 adapter builds its client with config.LoadDefaultConfig, which only picks the region up from the environment. The other S3 ESTI jobs go through bootstrap-test-lakefs, which runs aws-actions/configure-aws-credentials with aws-region: us-east-1 and so exports AWS_REGION into the job. The compatibility-checks job in .github/workflows/lakectl-compatibility-tests.yaml never runs that action and sets no region, and no TestLakectl* test used the adapter before this PR.

Suggested fix, in the "Run lakectl tests" step:

         env:
           AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_REGION: us-east-1
           ESTI_AWS_ACCESS_KEY_ID: ${{ secrets.ESTI_AWS_ACCESS_KEY_ID }}

An alternative that covers any future caller is to default the region in newS3Adapter (config.LoadDefaultConfig(ctx, config.WithDefaultRegion("us-east-1"))), but the workflow change matches how the other S3 jobs are configured.

Side note: since the delete failed, the two 5 GiB objects from run 1460 were left behind under s3://esti-system-testing/lakectl-compat/1460/.

Generated by Claude Code