Fix MediaStore_Images_MediaTest#testInsertImageWithImagePath

Previously, for files created by shell, FuseDaemon didn't insert any db
row. Since FuseDaemon started scanning the file after file creation,
FuseDaemon started inserting db row for files created by shell. Test
is not aware of these new db rows.

Separated file creation that doesn't account for testing from the
actual test that counts for db rows of test files.

Test: atest MediaStore_Images_MediaTest
Bug: 148585977
Change-Id: Ia2dec102ced859b243b187cd9f829dc00110fdd4