Merge "aflags: make flag storage error message more user-friendly" into main...

Merge "aflags: make flag storage error message more user-friendly" into main am: 1986c86b am: 1958c702

Original change: https://android-review.googlesource.com/c/platform/build/+/2995977



Change-Id: I4e0647e616102839d2e8445f3c72cfe6a9c4b44d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>