More authentic barrows rewards

Von and I had an extensive discussion/research session in the contributors discord, based on our beliefs that the current barrows rewards are not entirely authentic. Big, big, big thanks to Von for his major contribution here. He deserves more credit than I do.

What has been done in this MR?

• Removed the drops for 60 runes, which demonstrably came from an inauthentic (post-2009) RoW drop table from RS3 (just like the potions that were removed previously)
• Tweaked the barrows item chance to 1 in 450-58*number of killed brothers (same as both RS3 and OSRS), based on thorough research by and discussion with Von
• Players now always get number_killed_brothers + 1 rolls at the chest.
• Reworked non-barrows item quantities by cross-referencing OSRS, RS3, and Arios. Our previous quantities per roll were too generous, because the Arios guys likely did not realize that e.g. 850 mind runes resulted from players simply hitting the mind rune roll multiple times. (This may also be why the Arios implementation rng'ed the number of rolls, rather than always awarding 7 - to them the varying number of item types awarded may well have appeared random.)
• Slightly rewrote the roll algorithm so that barrows and non-barrows items are now rolled intermixed, as opposed to previous behavior of first giving out all barrows items and then all non-barrows items. This makes no difference for what you receive, only for the order in which the items are presented to you.

What should testers check?

• That the rewards and their rates seem reasonable, taking into account the number of brothers killed. They may seem a bit nerfed compared to the live game; this is expected.

• I have tested these changes thoroughly.
• I used the relevant Thanos/Zaros tool for any JSON edits where possible, and have attached screenshots of any changes.