Fix crash loop due to broken packages.xml around updated-package

Symptom:
Device cannot boot up due to NPE during package scan.

Root Cause:
/data/system/packages.xml is broken with an unexpected <updated-package>
element even though there's no corresponding <package> element.
When a system apk is installed, the system apk is registered
as a <package> element in the packages.xml.
When updated with a newer apk in /data, the data apk is registered as
a <package> and the system apk is moved to <updated-package>.
If a user triggers "Uninstall updates" but the device cannot complete
uninstallation processing due to any critical problem like system
freeze, the package.xml can be broken because the <package> for the
data apk is removed once but the <updated-package> for the system apk
remains wrongly.

Solution:
In this case, this change ignores the inconsistent <updated-package> and
installs the system apk as non-updated system app.

Test: forcibly stop "Uninstall updates" processing with JDB
      as described in b/143251299 and check system restart behavior
Bug: 143251299
Change-Id: I48b6957d19f5d60d08d2e5ba48fa1d7bf42fdcfe