Move GradientDrawable stroke fields back to grey list

The following fields are still lacking public getters:
Landroid/graphics/drawable/GradientDrawable$GradientState;->mStrokeDashGap:F
Landroid/graphics/drawable/GradientDrawable$GradientState;->mStrokeDashWidth:F
Landroid/graphics/drawable/GradientDrawable$GradientState;->mStrokeWidth:I

Removed the maxTargetSdk from the @UnsupportedAppUsage
annotation.

Bug: 132971065
Test: N/A
Change-Id: Id19452a8db6cda43c7d1b3c3c5ee74468c6de4e1