Old item identifiers still show up in the command completion screen

Steps to Reproduce:

1. Enable cheats;

2. Type /give @s and put the old name of any item.

Observed Results:
The name shows up.

Expected Results:
Only the new names show up, with the old ones still being supported.

Screenshots/Videos attached: Yes

Notes: Showing both can be confusing to new users, and hiding the old names wouldn't have any negative impact as they'd still work.