[flexiglass] Force garbage collection after successful authentication.

This reverts commit 10f024bb577d91c471ac6efff6c6a6d94160a5d4.

Reason for revert: unit test passes.

Fix: 308826153
Test: Unit tests pass.
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Change-Id: Ie097ae15f5308a6b0cc1e62e5eaac0c347a4a039
2 files changed