Allow inferred merge configs. am: 96d45412aa am: 42a14b7136 am: b31f9d57ff am: d74b740104

Original change: https://android-review.googlesource.com/c/platform/tools/treble/+/2025624

Change-Id: I3207c9e18ee19df17f7d3223bc241024ee16bfce