filter to only apple (vpp) apps in refresh job (#37506)

<!-- Add the related story/sub-task/bug number, like Resolves #123, or
remove if NA -->

The `refresh_vpp_app_versions` cron job wasn't updated to take Android
apps (a type of app store app) into account, leading to errors like
these ([internal Slack
thread](https://fleetdm.slack.com/archives/C03EG80BM2A/p1765934577063429)).

This adds a simple filter to the query that fetches the VPP apps.

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)

## Testing

- [x] Added/updated automated tests
- [x] QA'd all new/changed functionality manually

changes/jve-fix-filter-apps

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+- Updated the refresh_vpp_app_versions cron job to only attempt to refresh versions for Apple app store apps.