Prevent modal close on comment submission

What does this MR do and why?

This fixes a bug with submitting comments on an issue page. We show the user a warning modal when the comment has a secret in it, and this MR destroys the event, preventing the page from reloading while submitting the comment.

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Screenshots or screen recordings

Presently, when the warning modal appears, the page gets reloaded.

Before	After

How to set up and validate locally

1. Open any issue on gdk instance
2. Enter glrt-2CR8_eVxiioB1QmzPZwa to trigger warning modal.
3. The page should not reload when the modal appears.