AV1Enc: Fixing VBR quality issue am: 90d99d6fca am: 6324f6af54

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/22978768

Change-Id: Ib7b5aa5019cf4296600951262557d9abde5a9b02
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>