Namespace is required in /schedule clear

Unlike everywhere else in the game, the minecraft namespace is required in /schedule clear

Steps to reproduce:

• Make a data pack with a function named minecraft:test

• Go in-game

• Execute /schedule function test 1000d

• Observe it works fine

• Execute /schedule clear test

• Observe it says it doesn't exist

• Type /schedule clear t

• Note lack of suggestion

• Remove the t

• Note suggestion pops up

• Execute /schedule clear minecraft:test

• Observe it works