Disc header: leading zero in total time

Issue description:

Very small display issue in the disc headers: if the minutes are 0, the leading 0 is missing (or only the leading 0 is shown :wink:). Might apply to the seconds as well.

Also I think the hours do not need a leading zero, but if it is easier to apply a leading zero everywhere it does not disturb.

Screenshots:

+1 to hours not needing the leading zero

I can but it will be everywhere.

I think it looks better without the leading zero on the hours. On other views, e.g. genre details, it will be something like “3 days, 4:12:43”, so the zeronis not needed at all on the hours.