Drop spam throttling is affected by tick rate

Changing the tick rate affects that rate that drop spam throttling "decays" over time. If the tick rate is low, players cannot throw items as quickly.

To reproduce:

1. /tick rate 20
2. Quickly drop items from the creative inventory until the threshold is reached, causing you to drop only 1 item per second
3. /tick rate 1
4. Quickly drop items until the threshold is reached again
5. Try to drop more items, notice how it can take up to 20 seconds between drops

Code analysis:

LocalPlayer#tick() decrements dropSpamThrottler every tick, but MultiPlayerGameMode#handleCreativeModeItemDrop() increments dropSpamThrottler by 20 regardless of the tick rate.