DevelopmentSettings: initialize recovery update property at boot

Android behavior has changed to load & trigger build.prop & default.prop
at every boot.  Once data is mounted, it reloads & triggers properties
set by the user.  If we set persist.sys.recovery_update to true in build.prop
or default.prop, the user's preference will never be honored.  Instead,
ensure the default always comes from userdata.

Accompanying patches to remove the default properties are required.

OPO-490
Change-Id: I3a5245088059f083554063ba6d345783114fa7a0
(cherry picked from commit 55abf844)