Merge "<matrix><hal> optional attr has default value true." into main am: 7ebd846faf

Original change: https://android-review.googlesource.com/c/platform/system/libvintf/+/2836442

Change-Id: Iba52bd51530b515aa4616841d699f0cf99f57c01
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>