Verify that "run_exports" in shards doesn't copy to not-shards especially in postgresql

[dholth]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

postgresql support only uses sharded repodata and generate monolithic repodata from there.

Check that we don't add run_exports to monolithic repodata in this case.

Additional Context

No response