Set _modifier=_MODIFIER_MEDIA_SCAN for existing db rows

For existing database rows, we should set _modifier as
_MODIFIER_MEDIA_SCAN to avoid unnecessary rescanning of files.
Added UPDATE SQL query to set _modifier=_MODIFIER_MEDIA_SCAN

Bug: 179680144
Test: presubmit
Change-Id: I3b9bcdcf4ee688afdee5ee13d4e6c9237b0e2032
(cherry picked from commit d2fab45dcbc78c99293847b6870dc0fa109db698)
1 file changed