"bot users sync" uses reaction

[RiverCrimea]

Before the "bot users sync" subcommand was created, the bot used the following rules consistently:

1. If a command has no visible output, react to the command.
2. If a command does have visible output, do not react to the command. Instead, merely give the visible output.

The new subcommand both has visible output and reacts to the command. For consistency, the reactions should go away.