Set persist.sys.device_provisioned vendor-init-readable.

`persist.sys.device_provisioned` is set (more precisely, "will be set",
via internal change in ag/7567585) by system_server based on device
privisioning state. This CL grants vendor_init to set up action triggers
based on the property value.

avc:  denied  { read } for property=persist.sys.device_provisioned pid=0 uid=0 gid=0 scontext=u:r:vendor_init:s0 tcontext=u:object_r:system_prop:s0 tclass=file permissive=0

Bug: 131702833
Bug: 132906936
Test: Set an init trigger that waits on `persist.sys.device_provisioned`.
      Check that there's no longer a denial.
Change-Id: I64e50bd31c90db4b3bdd3bd014a90d7bef708b57
Merged-In: I64e50bd31c90db4b3bdd3bd014a90d7bef708b57
(cherry picked from commit 264a929edbb2f635259821bd6cb9177626a86870)
diff --git a/public/property_contexts b/public/property_contexts
index 061d1fc..566883c 100644
--- a/public/property_contexts
+++ b/public/property_contexts
@@ -161,6 +161,7 @@
 # vendor-init-readable
 apexd.status u:object_r:apexd_prop:s0 exact enum starting ready
 dev.bootcomplete u:object_r:exported3_system_prop:s0 exact bool
+persist.sys.device_provisioned u:object_r:exported3_system_prop:s0 exact string
 persist.sys.usb.usbradio.config u:object_r:exported3_system_prop:s0 exact string
 sys.boot_completed u:object_r:exported3_system_prop:s0 exact bool
 sys.retaildemo.enabled u:object_r:exported3_system_prop:s0 exact int