init.usb.rc: specify user manually

Merging as a separate CL due to a log showing up
related to this on hwasan (is a prebuilt pulling
this in?)

Bug: 276813155
Test: boot cf
Change-Id: I19f7fc51c937d0eb1ee17781fc5d201a0972c4b0
diff --git a/rootdir/init.usb.rc b/rootdir/init.usb.rc
index 0730cce..dde784e 100644
--- a/rootdir/init.usb.rc
+++ b/rootdir/init.usb.rc
@@ -18,6 +18,7 @@
     disabled
     updatable
     seclabel u:r:adbd:s0
+    user root
 
 on property:vendor.sys.usb.adb.disabled=*
     setprop sys.usb.adb.disabled ${vendor.sys.usb.adb.disabled}