(Fix) Lifetime donor download slot check

[thatonePRguy]

This PR adjusts the Lifetime Donor download slot limit enforcement criteria. The existing check enforces the download slot limit on lifetime donors whenever their assigned group has a non-null download_slots value, due to the || condition in the if block.

Based upon the verbiage in the lifetime donor blade, I do not believe this is the expected behavior. See donation/index.blade.php#L48.

Removing $user->group->download_slots !== null from the if block defers the evaluation of slot limits for all non-lifetime donors when the slot system is enabled to the checkDownloadSlots func which already gracefully handles null and non null slot limits.

[what-the-diff]

PR Summary

• Refined Application Decision-Making
  The way the application decides to use download slots has been simplified. It now relies only on the user's membership status and if the slots system has been enabled. Previously, it used to also factor in the total download slots in a group which complicated the process.

[Roardom]

This would allow any donor to very easily do a full peer scrape of the entire tracker. Not very secure?

[thatonePRguy]

This would allow any donor to very easily do a full peer scrape of the entire tracker. Not very secure?

I don't disagree, but my interpretation of the existing code is that is the intended behavior? If you or @HDVinnie would be open to altering the verbiage of the donor advertisement to something along the lines of "Increased download slots" and a preference for how "increased" should be handled, I would be happy to modify the PR accordingly.

If you have any other preferred approach I'd be happy to discuss further as well. Cheers

[Roardom]

I would personally prefer removing everything related to donations, but that would be vinnie's decision. Seeing as this "perk" was never implemented, I think removing it from the verbiage would work better than additionally adding it so late now. Up to vinnie.