fix(mon-pages): centre a cell that holds one line

A plain cell pads its text to the row height, so it reads centred on a
single-line row. The state tag and the highlighted value did not: both
are shorter than that and their wrapper aligns to the top, which left
them sitting a few pixels high of the text beside them.

Both now carry the row height themselves and centre within it. A row
grown by a wrapping cell is untouched, the box being taller than its
minimum by then.

CMK-38149

Change-Id: Id56cac6347e1e4d46e4531f1e69e57747a934345