Remove pointless `sample` calls when StateFlow exists

`sample` launches coroutines to collect the value from a flow as it
updates. This is not needed for StateFlows, when the value can be
queried as needed.

This should reduce continuations.

Also, change how StatusBarStateControllerImpl collects shade expansion.
isAnyExpanded uses legacy behavior that updates on bouncer expansion.

Bug: 405159039
Test: perfetto analysis
Flag: EXEMPT performance fix
Change-Id: Iba5df3db2907df2f130ac9fe2b437d4dc284a345