va-file-input-multiple: Fix multiple emits of vaMultipleChange

[ataker]

Chromatic

https://file-input-mult-event-double-emit--65a6e2ed2314f7b8f98609d8.chromatic.com

Description

Closes va-file-input-multiple emits twice on file upload #3549

A call of handleFile was added to the render function of va-file-input when read only was added. The handleFile emits vaChange which caused the second vaMultipleChange to fire in va-file-input-multiple. I added a parameter to conditionally emit change and set it to false for this call of handleFile.

Additionally this issue wasn't caught by tests because we only waited for the input change. Added waitForChanges to the page before checking how many times vaMultipleChange was emitted.

QA Checklist

• Component maintains 1:1 parity with design mocks
• Text is consistent with what's been provided in the mocks
• Component behaves as expected across breakpoints
• Accessibility expert has signed off on code changes (if applicable. If not applicable provide reason why)
• Designer has signed off on changes (if applicable. If not applicable provide reason why)
• Tab order and focus state work as expected
• Changes have been tested against screen readers (if applicable. If not applicable provide reason why)
• New components are covered by e2e tests; updates to existing components are covered by existing test suite
• Changes have been tested in vets-website using Verdaccio (if applicable. If not applicable provide reason why)

Acceptance criteria

• QA checklist has been completed
• Screenshots have been attached that cover desktop and mobile screens

Definition of done

• Documentation has been updated, if applicable
• A link has been provided to the originating GitHub issue (or connected to it via ZenHub)