Add boot_status_prop for boot completed props

Assigning a new context boot_status_prop for following two properties:
- sys.boot_completed
- dev.bootcomplete

Bug: 154885206
Test: boot cf_x86 and crosshatch, see no denials
Change-Id: Ieadabf90a9a1b54b52a1283bd648c11c95d558dd
Merged-In: Ieadabf90a9a1b54b52a1283bd648c11c95d558dd
(cherry picked from commit 2973c9605555c119243ef85119576b2d01a12060)
diff --git a/private/property_contexts b/private/property_contexts
index aeb391c..640ae88 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -499,13 +499,13 @@
 # vendor-init-readable
 apexd.status u:object_r:apexd_prop:s0 exact enum starting activated ready
 
-dev.bootcomplete u:object_r:exported3_system_prop:s0 exact bool
+dev.bootcomplete   u:object_r:boot_status_prop:s0 exact bool
+sys.boot_completed u:object_r:boot_status_prop:s0 exact bool
 
 persist.sys.device_provisioned  u:object_r:exported3_system_prop:s0 exact string
 persist.sys.theme               u:object_r:theme_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
 sys.user.0.ce_available u:object_r:exported3_system_prop:s0 exact bool
 sys.vdso                u:object_r:exported3_system_prop:s0 exact string