init: microdroid: Enable WORLD_WRITABLE_KMSG

Microdroid VMs may be "debuggable" even on non-debuggable hosts (Android
releases) so unconditionally enable /dev/kmsg_debug and let Microdroid
internally control whether the device is used or not.

Test: vm run-app --debug full # check logs
Bug: 442346413
Flag: EXEMPT debug only
Change-Id: I44c27c64562d6802d42502105a4114bc4d4a066c