StatusBarContentInsetsProvider: call start in init when flag is disabled

This is to fix the case when the flag is disabled, and nothing is
calling start.

Test: StatusBarContentInsetsProviderTest.kt
Flag: com.android.systemui.status_bar_connected_displays
Bug: 362720336
Fixes: 377618404
Fixes: 377599051
Change-Id: I04a59d55d0615156120f9f56211a7405f5c0a8ff
2 files changed