[chord] add log for arrow flight read

[JNSimba]

Proposed changes

Issue Number: close #xxx

Problem Summary:

Describe the overview of changes.

Checklist(Required)

1. Does it affect the original behavior: (Yes/No/I Don't know)
2. Has unit tests been added: (Yes/No/No Need)
3. Has document been added or modified: (Yes/No/No Need)
4. Does it need to update dependencies: (Yes/No)
5. Are there any changes that cannot be rolled back: (Yes/No)

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[Copilot]

Pull request overview

This PR adds additional logging around Arrow Flight SQL reads in the Spark Doris connector to help observe query submission timing and per-batch/partition read progress.

Changes:

• Log per-batch load metrics (rows + elapsed time) when reading Arrow batches.
• Track and log per-partition totals (batch count and total rows) when closing the reader.
• Log query submission latency for Flight SQL execution.

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