Merge "Remove dead CompatibilityMatrix::getSourceMatrixLevel." into main am: 4ce40d5b7a

Original change: https://android-review.googlesource.com/c/platform/system/libvintf/+/2898309

Change-Id: Ic056d9f438293812a17bfb539d39dfd8c42d9d55
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>