Fix preserving app links user selection on package update

The wrong set of domains was being used for domain retainment during
migration. A test was added to check both verified and selected state
preservation on update.

Test: atest DomainVerificationPackageTest#migratePackageSelected

Bug: 205009465

Change-Id: I2c864a34f356e32948cbc4e5d249e12c691a5726