F3 + T still reloads loot tables and advancements despite the addition of the /reload command

Relates to MC-115148

The bug

The key combination F3 + T still reloads loot tables and advancements despite the fact that the /reload command was added in 17w18a.
It even runs the functions tagged in minecraft:load.

How to reproduce

Loot tables

1. Open a world
2. Create the following folder structure in the data folder of the world
   • loot_tables
     • custom
       • test.json (attached file)
3. Create a chest with the loot table custom:test

   /setblock ~ ~ ~ chest default replace {LootTable:"custom:test"}
   

4. Open the chest
   → It contains a stone item
5. Change the test.json file (with a text editor) to give minecraft:dirt as loot
6. Repeat steps 3 and 4
   → The chest contains still a stone item
7. Press F3 + T
8. Repeat steps 3 and 4
   → The chest contains a dirt item

Advancements

1. Open a world
2. Create the following folder structure in the data folder of the world
   • advancements
     • custom
       • root.json (attached file)
3. Walk around
4. Open the advancement view
   → You will not see the custom advancement (beacon icon)
5. Press F3 + T
6. Repeat steps 3 and 4
   → You will see the custom advancement