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