Fix/FSRS progress sometime shows 0 reviews

[L-M-Sherlock]

source: https://forums.ankiweb.net/t/anki-24-10-beta/49989/223?u=l.m.sherlock

If the optimization is done in 100ms, the thread cannot update the progress before the function return the results.

#3420 cannot deal with this case.

[dae]

Appreciate the fix as always :-) But blocking the main thread like that is not ideal, nor is adding 100ms even when not necessary. @abdnh, can you think of a better approach?

[L-M-Sherlock]

I think it's better than my previous idea.

progress_thread.join().ok();

But it still blocks the main thread.