[SB][Chips] Align 3-2-1 countdown within the center of the chip.

Only really noticeable with the `1`, because we're using the
`neverDecreaseWidth` modifier and the `1` is narrower than other numbers
so it has extra space that needs to go somewhere.

Fixes: 412425303
Flag: com.android.systemui.status_bar_chips_modernization
Test: In RTL language, start screen recording -> verify 1 in 3-2-1
countdown is centered. Verify the same for LTR language

Change-Id: I2ac1e1adc7339c95ecdfd8e6d00502d6f83b29bd