Update predictive back progress interpolator for dialogs

Bug: 332512902
Flag: ACONFIG com.android.systemui.predictive_back_animate_dialogs TRUNKFOOD
Test: Manual, i.e. analysing screenrecordings and verify that there are no more animation jumps at the start/end of the back animations
Change-Id: I22400eb4547582739373c968282b160c4450d42c