Updating a PDF in an existing, completed project

[jupiter007]

Describe the bug
When a user chooses to upload another plan for a completed project with an associated DMP PDF, and the select another PDF, the user does not get any feedback that the update has been made and remains on the "Update plan" page.

To Reproduce
Steps to reproduce the behavior:

1. Go to the dmp tool on stage, and click on "Upload Plan" link at the top
2. Select a project that is registered and has a DMP PDF associated with it
3. Click the "Update" link for that project
4. Click on "Project name & PDF upload" link under "Plan setup"
5. Click the "Choose File" button, and select a different PDF than the one already associated with the plan
6. Then click the "Update" button
7. The user remains on the page, and receives no feedback that the PDF has been updated.

Expected behavior
Not certain what feedback will work best. At minimum, we should message the user that the PDF was updated, and we probably want to redirect them back to the Upload Plan dashboard.

Screenshots

[bofstein]

I could not repro, using Chrome and this plan; I see the plan and an update option

https://dmptool-stg.cdlib.org/dashboard/dmp/20240807-b9cf14b4cebb