[SB][Clock] Use tnum spacing if status bar clock has seconds enabled.

We don't want tnum spacing for most user's clocks, but we should use it
for anyone who has seconds enabled so that the notification icons aren't
moving around every second.

Bug: 411157074
Flag: EXEMPT bugfix
Test: Enable seconds using TunerActivity -> verify clock has tnum
spacing, notif icons don't move every seond
Test: Disable seconds -> verify clock has proportional spacing, notif
icons may move a bit each minute depending on the time
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:6ac52f3b21bd43f901200a678c4b4ad82da4fd93)
Merged-In: I34548cdc48b1020bd86c5817dd83b9c934fad63c
Change-Id: I34548cdc48b1020bd86c5817dd83b9c934fad63c