Fix user feedback on clicking Audit CSV export button

Summary

Steps to reproduce

• Sign in as a Bank user (org_admin1@example.com)
• You'll need an Audit
  • Inventory -> Inventory Audit -> New Audit
  • Select a storage location (ex: Bulk Storage Location)
  • Select an item that we are auditing form the dropdown (ex: Adult Briefs Medium/Large)
  • Enter any qty as how many we have (17)
  • Click Confirm Audit and confirm in the pop-up
  • This shows you a list of items you audited and items you didn't audit, go to the bottom and click Finalize Audit and confirm
• Now that you have an Audit, navigate again to Inventory -> Inventory Audit you will see your audit
• Click Export Audits
• The button changes to Please wait... while it generates the CSV
• .... but it never changes

For this, ideally the button would change back to Export Audit after the CSV has been generated.

Things to consider

We aren't sure exactly how to detect that the CSV has been generated; if it gets complicated please share here what your plan is.

Also consider if there is a general solution for all of our Export CSV buttons.

Criteria for Completion

• Button changes back
• System test that verifies the behavior
• No update needed to user guide

Start by reproducing the Inventory Audit flow and locating the Export Audits button and its related system test. Trace when the CSV download completes, then verify that the button returns to its export label and add the requested system-test coverage.