Run logd only when debug_level is set

When debug_level is set to none, logd is not started at all.

Bug: 200914564
Test: run a VM with and without --debug full
Change-Id: Idb1ea3753067242eb0dcd53d3ae783e9e947ca32
diff --git a/microdroid/bootconfig.full_debuggable b/microdroid/bootconfig.full_debuggable
index 0d0457c..fd8a83e 100644
--- a/microdroid/bootconfig.full_debuggable
+++ b/microdroid/bootconfig.full_debuggable
@@ -9,3 +9,6 @@
 # ro.adb.secure is still 0 (see build.prop) which means that adbd is started
 # unrooted by default. To root, developer should explicitly execute `adb root`.
 androidboot.adb.enabled=1
+
+# logd is enabled
+androidboot.logd.enabled=1