Dataset Loses Harvest Object on WAF file Timestamp Change

related issue: https://github.com/GSA/data.gov/issues/4505

## Summary:
When the timestamp of a WAF source file changes without any actual content modification, the metadata information disappears from the UI.

The root cause is the the harvest_object_id does not change with the new harvest_object_id.
This was confirmed through the following API calls:
/api/action/package_show?id=
/api/action/package_search?q=id:

Additionally, testing on the most recent version of CKAN with only the ckanext-harvest and ckanext-spatial extensions replicated the problem.

### Observations from Testing:
1. Manually run `ckan search-index rebuild ` resolved the issue, as the above API calls return correct value of harvest_object_id.

2. Found the code block which should refresh the solr index:
https://github.com/ckan/ckanext-spatial/blob/master/ckanext/spatial/harvesters/base.py#L709C1-L710C70

Testing with the following code changes yielded positive results:
Invoking `package_update ` instead of `package_index.index_package` resolved the issue.
OR
Addition of `model.Session.commit()` before invoking package_index.index_package also resolved the issue.
OR
calling `rebuild` index instead of package_index.index_package does not solve the issue unless `model.Session.commit()` was called before invoking the `rebuild`.

It seems that the assumption that `package_index.index_package` doesn't need a database commit to refresh Solr isn't valid based on the tests conducted above.

Any alternative solutions to address this issue?

Start with ckanext/spatial/harvesters/base.py around lines 709-710 and reproduce the issue using the listed package_show and package_search API calls. Compare the observed effects of package_update, package_index.index_package, rebuild, and committing the session first. Done means the harvest_object_id remains correct in the API responses and the metadata stays visible after a WAF timestamp-only change.

Written by the indexing model from the issue text.