Improve statistics test coverage

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

It is clear that the current statistics code is lacking tests . For example I was about to delete code https://github.com/apache/arrow-datafusion/pull/8172 but thankfully @berkaysynnada pointed out the code was actually different, yet not tests failed.

I spent some time auditing the codebase for tests, and here is what I found:

## places that I think could do with some additional coverage

These places have tests, but we should review them to ensure that the coverage is adequte

Here are the places that do have tests, but the coverage probably needs to be reviewed
- [ ] LocalLimitExec: https://github.com/apache/arrow-datafusion/blob/fdf3f6c3304956cd56131d8783d7cb38a2242a9f/datafusion/physical-plan/src/limit.rs#L833
- [ ] UnionExec: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/union.rs#L696
- [ ] FilterExec: https://github.com/apache/arrow-datafusion/blob/e1c2f9583015db326b3439897376f14f6b83a99a/datafusion/physical-plan/src/filter.rs#L455

## places that appear to be lacking coverage at all

Here are `impl ExecutionPlan` that implement `statistics` but I didn't find *any* tests (though I could have missed them)
- [ ] `get_statistics_with_limit`: https://github.com/apache/arrow-datafusion/blob/e54894c39202815b14d9e7eae58f64d3a269c165/datafusion/core/src/datasource/statistics.rs#L34-L33
- [ ] `Join` statistics: https://github.com/apache/arrow-datafusion/blob/e642cc2a94f38518d765d25c8113523aedc29198/datafusion/physical-plan/src/joins/utils.rs#L455-L454
- [ ] `HashAggregateExec` https://github.com/apache/arrow-datafusion/blob/67d66faa829ea2fe102384a7534f86e66a3027b7/datafusion/physical-plan/src/aggregates/mod.rs#L888-L887
- [ ] `WindowExec`: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/windows/window_agg_exec.rs#L250
- [ ] `BoundedWindowExec`: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/windows/bounded_window_agg_exec.rs#L311

### Describe the solution you'd like

Review and add coverage as necessary to locations above

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start by reviewing the statistics implementations and existing tests at LocalLimitExec in physical-plan/src/limit.rs, UnionExec in physical-plan/src/union.rs, and FilterExec in physical-plan/src/filter.rs, then inspect get_statistics_with_limit in core/src/datasource/statistics.rs and the listed Join, HashAggregateExec, WindowExec, and BoundedWindowExec locations. Done means the identified statistics paths have adequate tests, including coverage for locations that currently appear untested.

Written by the indexing model from the issue text.