AoC: If linked username is not shown in leaderboard, include link to the regular leaderboard

[janine9vn]

Often people join the leaderboard, link their account, and then use our leaderboard command. An issue pops up if the leaderboard refresh is still on cooldown. An error message pops up and prevents the user from viewing the current leaderboard until the leaderboard refreshes.

Instead, we should still show an error message indicated we cannot find their username, but still show the regular leaderboard embed so they can still view leaderboard information.