Qt: Set default selection to "No" when closing while memory card is busy

[resadent]

Description of Changes

Set the dialog default button pressed to "No".

Rationale behind Changes

It may prevent people from accidentally erasing their memory cards. Fixes #13131.

Suggested Testing Steps

Pause a game when it is writing to a memory card, then close the emulator.
I did is in God of War II while it was saving and it worked fine.

Did you use AI to help find, test, or implement this issue or feature?

No.

[TheTechnician27]

This does not fix #13131. The person posting the issue was using the FSUI, which is a tricky problem that I tried and failed to solve.

As you can see in the screenshot above, PCSX2 master already defaults to 'No' in the Qt UI. As far as I can tell, this PR does nothing to change the behavior of current master. The only line of code changed is if (res != QMessageBox::Yes) to if (msgbox.exec() != QMessageBox::Yes), and I can't immediately tell what that's supposed to be doing, because the current code clearly works.

[TheTechnician27]

Also, incidentally, this pulls in @JordanTheToaster's macOS FFMPEG dependency commit by mistake. But there's no reason to merge the actual commit either, as it does not ostensibly do anything, let alone what is advertised.

[SternXD]

yeah, this isn't related to the issue at all

[TheTechnician27]

Closing as:

1. Not addressing the issue [Feature Request]: Set default selection to "No" when closing while memory card is busy #13131 it claims to address.
2. Instead "fixing" an alleged issue shown in screenshot which does not exist on current master.
3. Inexplicably removing the grab for the dialog parent lock.
4. Otherwise doing nothing that subjectively or objectively improves functionality or organization in any way.

[resadent]

Thanks for the review, sorry I did not understand completely the issue.