Add `CoalesceBatchesExec` to `NestedLoopJoinExec`

### Is your feature request related to a problem or challenge?

The `NestedLoopJoinExec` operator can produce output batches with fewer rows than the configured batch_size. To improve performance, we should add a `CoalesceBatchesExec` operator after it.

When running the following SQL query, the metrics show that the NLJ operator is producing very small batches: (NLJ "output_rows=6" "output_batches=3")
```
explain analyze select count(*) from range(2,8194) as t1 join range(2,24576) as t2 on t1.value * t2.value < 10;
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type | plan |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | ProjectionExec: expr=[count(Int64(1))@0 as count(*)], metrics=[output_rows=1, elapsed_compute=525ns] |
| | AggregateExec: mode=Final, gby=[], aggr=[count(Int64(1))], metrics=[output_rows=1, elapsed_compute=17.663µs] |
| | CoalescePartitionsExec, metrics=[output_rows=24, elapsed_compute=17.979µs] |
| | AggregateExec: mode=Partial, gby=[], aggr=[count(Int64(1))], metrics=[output_rows=24, elapsed_compute=2.412497ms] |
| | ProjectionExec: expr=[], metrics=[output_rows=6, elapsed_compute=1.17µs] |
| | NestedLoopJoinExec: join_type=Inner, filter=value@0 * value@1 < 10, metrics=[output_rows=6, build_input_batches=1, build_input_rows=8192, input_batches=3, input_rows=24574, output_batches=3, build_mem_used=65632, build_time=32.303µs, join_time=2.490000275s] |
| | LazyMemoryExec: partitions=1, batch_generators=[range: start=2, end=8194, batch_size=8192], metrics=[] |
| | RepartitionExec: partitioning=RoundRobinBatch(24), input_partitions=1, metrics=[fetch_time=42.542µs, repartition_time=1ns, send_time=396.529µs] |
| | LazyMemoryExec: partitions=1, batch_generators=[range: start=2, end=24576, batch_size=8192], metrics=[] |
| | |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.834 seconds.

```

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Additional context

https://github.com/apache/datafusion/blob/d00a085d5a5acde73a7667e8c73b5f0077d8a960/datafusion/physical-optimizer/src/coalesce_batches.rs#L63-L79

`CoalesceBatchesExec` is added after `HashJoinExec`
```
explain analyze select * from range(2,8194) as t1 join range(2,24576) as t2 using(value);
+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type | plan |
+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | CoalesceBatchesExec: target_batch_size=8192, metrics=[output_rows=8192, elapsed_compute=10.689µs] |
| | HashJoinExec: mode=Partitioned, join_type=Inner, on=[(value@0, value@0)], projection=[value@0], metrics=[output_rows=8192, build_input_batches=24, build_input_rows=8192, input_batches=24, input_rows=24574, output_batches=24, build_mem_used=275776, build_time=446.567µs, join_time=216.082µs] |
| | CoalesceBatchesExec: target_batch_size=8192, metrics=[output_rows=8192, elapsed_compute=20.988µs] |
| | RepartitionExec: partitioning=Hash([value@0], 24), input_partitions=24, metrics=[fetch_time=1.975326ms, repartition_time=45.457µs, send_time=6.671µs] |
| | RepartitionExec: partitioning=RoundRobinBatch(24), input_partitions=1, metrics=[fetch_time=15.114µs, repartition_time=1ns, send_time=976ns] |
| | LazyMemoryExec: partitions=1, batch_generators=[range: start=2, end=8194, batch_size=8192], metrics=[] |
| | CoalesceBatchesExec: target_batch_size=8192, metrics=[output_rows=24574, elapsed_compute=60.501µs] |
| | RepartitionExec: partitioning=Hash([value@0], 24), input_partitions=24, metrics=[fetch_time=1.925668ms, repartition_time=153.331µs, send_time=34.965µs] |
| | RepartitionExec: partitioning=RoundRobinBatch(24), input_partitions=1, metrics=[fetch_time=28.387µs, repartition_time=1ns, send_time=1.025µs] |
| | LazyMemoryExec: partitions=1, batch_generators=[range: start=2, end=24576, batch_size=8192], metrics=[] |
| | |
+-------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row(s) fetched.
Elapsed 0.002 seconds.
```

Start with the coalesce_batches.rs section linked in the issue and compare how CoalesceBatchesExec is placed after HashJoinExec. Trace the NestedLoopJoinExec plan construction and identify the relevant physical optimizer entry point. Validate the change with the provided EXPLAIN ANALYZE query, confirming that NLJ output is coalesced into larger batches.

Written by the indexing model from the issue text.