Fix PackageManagerServiceHostTests disk usage

It seems adb shell stop/start has a bug with taking up disk
space. For now, use a full reboot of the device for each
test step.

This will double the already extremely long test time, so the
entire PackageManagerServiceHostTests module has been moved
to postsubmit, except for tests annotated @Presubmit, of which
there are none as of this change.

Bug: 159540015
Bug: 159256824

Test: atest PackageManagerServiceHostTests

Change-Id: I67da61cb02baa572fc298e6f617d6e53ec2c4724