The URL of the leaderboard for competitions should be better chosen

[omichel]

Currently the URL for a competition leaderboard is like https://competition.webots.cloud/run?version=R2022b&url=https://github.com/omichel/my-competition/blob/main/worlds/robot_programming.wbt&type=competition

Instead, it would be better like https://competition.webots.cloud/leaderboard?version=R2022b&url=https://github.com/omichel/my-competition/blob/main/worlds/robot_programming.wbt