Fix TimeUtils.formatDuration for exactly one of a unit

Previously printing a duration where a unit (except ms) was one and the
next smallest unit was zero would result in the duration being being
expressed in the next smallest unit. For example 1m0s0ms would be
formatted as 60s0ms.

Update testFormatHugeDuration to supporting times > 999 days
The implementation was fixed in 3d1933c4

Change-Id: I9d609f7a0f82755ea653a205293a6e3785a10d1e