Removed intercept metas.

Removed the currently introduced intercept meta (#3792, oh the irony).
Comments added to prevent this from happening again.

The report generation now goes this way :
* we remove the current game mode from the list of all possibles game modes,
* we remove 1 or 2 random game modes,
* if not malf and the AI is not intercepting the report, we _replace_ (not insert) a random game mode in the list with the current game mode (so that we always have 4 or 5 modes in the list),
* we shuffle the list, to prevent meta (with the current mode being the only one randomly placed).

Fixes #3854.