[test][assetwidget] Improve algorithm migration test

It ensure that the declaration loaded matches the one
from the migrated algorithm.
4 jobs for 275_fix_algorithm_migration in 26 minutes and 56 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed build_linux_36 #205486
docker

00:11:37

90.0%
passed build_linux_37 #205487
docker

00:11:21

90.0%
passed build_macosx_36 #205484
macosx

00:26:56

90.0%
passed build_macosx_37 #205485
macosx

00:26:17

90.0%