Make function not static and remove static class variable

getIgnoredHeadings() was the last static function in this class

Change-Id: I289032ef67bfc0c74ec9fbb0469d17c537c9b4ab
Remove DeletePagesJob::build()

Pointless wrapper when we only call it once

Change-Id: Ia358c844bbbd71ff63e08e2105c658e14289ae49