storageproxyd: Start only a single binder thread am: 209890c07d

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/24168425

Change-Id: Iac79aa1c5fe353a6d5e220987689859fa6a33c37
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>