Switch to "ro.vendor" group for Android property

Originally we use "debug" group to save the configuration. However,
the value should be read-only at run-time. "ro.vendor" is a better
group for the usage case.

Bug: 189059445
Test: android.media.cts.AdaptivePlaybackTest
Change-Id: I04cfd8498b6bafdd0a4ee6ea16d002c9f50bdc0d