Fix SettingsXml start tag logic

Don't move to next tag if the current tag is the START_TAG. The initial
implementation assumed domain verification state would write to a new
XML file, but it ended up being stuffed into packages.xml, so the
start tag is already read in the initial switch that calls into
DomainVerificationService.

Bug: 180527086

Test: atest DomainVerificationPersistenceTest

Change-Id: I623afb08985bf5377cb9ae240805aae5db9cd820