Alignment and size fixes for CountingTimerView

-Vertically center text in the middle of the circle
-Do not resize H/M/S labels even when the rest of the text changes in size
-Fix text overlap with circle
-Vertically align H/M/S labels at the top of text

Bug: 7254767 UI: Text overlapping the timer circle when the countdown goes -ve
Change-Id: I453d50a00d2ac589c7f9568635c6e41aa6263e34