Download All button does nothing when there is only one attachment previewed

Describe the bug
If the user runs a query for Collections Objects with attachments, selects one, browses in forms, clicks the attachments icon, then presses Download All nothing will happen. This appears to be because a route to /attachment_gw/proxy is failing.

To Reproduce

1. Go to Queries
2. Search for Collection Objects with Attachments
3. Select one through using the checkbox
4. Click Browse in Forms
5. Select the attachment icon
6. Click Download All
7. Observe that nothing happens

Expected behavior
One image would be zipped and downloaded (same as if there were 2, or 3 etc)

Screenshots

Crash Report

N/A

Please fill out the following information manually:

• Browser: Firefox 138.0.4
• Specify 7 Version: 7.10.2.3
• Database Name: sp7demofish and beaty

Reported By
Beaty Biodiversity Museum

Additional context
Originally the button seems to have been disabled when there was a single attachment, however it passed QA at that time. #6052 (comment). This commit may also be relevant: 3f92de5