[MC-30946] Beacon regeneration speed is reduced compared to normal speed

The bug

The regeneration on the beacons works at only 5/8 the normal regeneration speed. Beacon regeneration applies every 80 ticks instead of every 50, so the reduction in healing rate compared to a potion is 37.5%.

How to reproduce

To test, run the following commands:

/gamerule naturalRegeneration false
/gamerule commandBlockOutput false
/scoreboard objectives add health health
/scoreboard objectives add prev_health dummy
/scoreboard objectives add time minecraft.custom:minecraft.play_time
/scoreboard objectives add time_since_healed dummy
/scoreboard objectives setdisplay sidebar time_since_healed

And then set up command block chain with the following commands (in order, with the first block being a repeating block, and all three blocks being unconditional and always active):

execute as @p if score @s prev_health < @s health run scoreboard players operation @s time_since_healed = @s time
execute as @p if score @s prev_health < @s health run scoreboard players set @s time 0
scoreboard players operation @p prev_health = @p health

And then run the following to damage yourself:

/teleport @s ~ ~20 ~