Add background flag to CI system update intent

Add flag to allow KEY_CI_ACTION_ON_SYS_UPDATE_INTENT_STRING
intent. This is needed
as the receiver service is modified to use
latest target version SDK which introduces Background
broadcast limitations.

Bug: 78634470
Test: On Device, verified that the intents are
      received by the service
Change-Id: I140c1988b241885a737413bd5f0b9c3cc63c4ea8