Change hour and minute alignment in text TimePicker

Fixes: 315085352

Flag: EXEMPT bugfix

The "hour" and "minute" text overlap when the fonts
are large. This uses the size of the "hour" text
and the "50sp" minimum to guarantee that the "hour"
can fit. With small fonts, the 50sp is used and the
"hour" is center aligned under the EditText. When
the fonts are large, the "hour" text is used to
size the space and the EditText is aligned to the
right of it.

Similarly, the minute text is center aligned under
its EditText when the fonts are small and left
aligned when the fonts are large.

Test: manual testing with small and large fonts

Change-Id: I8c0e4fba8e425c1959f875662daa5ca087256108