Converted sequence ticks to proper game ticks

As discussed in https://github.com/OpenRA/OpenRA/issues/6389 the `Tick:` in the sequence definitions is not actually a game tick, but a value in milliseconds that gets processed in a function that uses game ticks again. That is not only contra-intuitive for modders, but also poses a problem when using values that are not divisible by 40. This tidies this relic up with the help of an automated upgrade rule whose results have hand cleaned to avoid loosing inline comments.