fix: fix an issue where upcoming invoice doesn't have the nextPeriodCharges field

[tianrunhe]

Description

Fixes #9578

After #9551 landed, we noticed that the UPCOMING invoices do not have the nextPeriodCharges field. The culprit is that the function that produces those future invoices, makeUpcomingInvoice, does not have a return type check. This fix imposes that and populate the required fields.

Demo

Testing scenarios

• Upcoming invoices
  1. Upgrade an org to team tier
  2. Observe the upcoming invoices are present correctly

Final checklist

• I checked the code review guidelines
• I have added Metrics Representative as reviewer(s) if my PR invovles metrics/data/analytics related changes
• I have performed a self-review of my code, the same way I'd do it for any other team member
• I have tested all cases I listed in the testing scenarios and I haven't found any issues or regressions
• Whenever I took a non-obvious choice I added a comment explaining why I did it this way
• I added the label Skip Maintainer Review Indicating the PR only requires reviewer review and can be merged right after it's approved if the PR introduces only minor changes, does not contain any architectural changes or does not introduce any new patterns and I think one review is sufficient'
• PR title is human readable and could be used in changelog

[Dschoordsch]

Merging this now because I want to release it.