[SB][Chips] Only compose the chips if we have chips to show.

Recomposition is expensive and can cause performance regressions,
so don't compose the chips at all unless we know we have chips to show.

Fixes: 401241197
Bug: 372657935
Flag: com.android.systemui.status_bar_chips_modernization
Test: smoke test of chips (adding + removing all types of chips)
Change-Id: I553d74342f347467951aeeb10aa4b72e30f38c94