fix: record TakeExec output and I/O metrics

[skyshineb]

Problem

Closes #7227. The IoMetrics of the take operator are broken. The metrics such as output_bytes=0.0 B, output_batches=0, bytes_read=0 are not visible.

Example:
... Take: elapsed=350.781983256s, columns="_distance, _rowid, (vec)", metrics=[output_rows=10.00 K, elapsed_compute=302.52s, output_bytes=0.0 B, output_batches=0, batches_processed=1, bytes_read=0, iops=0, requests=0] ...

Cause

TakeExec was recording output row metrics inside map_batch, before the spawned take work had completed and before the final RecordBatch was emitted through DataFusion's metrics path. As a result,
output_batches, output_bytes, and ScanScheduler I/O metrics stayed at zero even when take work read data successfully.

Solution

This moves metric recording to the post-try_buffered result path, records the final RecordBatch with BaselineMetrics::record_poll, and records ScanScheduler I/O metrics after the actual take/read work
completes. The stream also finalizes baseline metrics and records one final I/O snapshot when it finishes.

Added a regression test covering output rows, output batches, output bytes, bytes read, IOPS, requests, and batches_processed.