Snap page does not show the right snap-id

[Celso Providelo]

See https://myapps.developer.ubuntu.com/dev/click-apps/4142/

It's showing "XnXOwlkNrPTnmtxIx1KsxWbrVaeIZiFT" which is the snap-id for "rolling-core", not "16" where assertions are a thing.

The view itself does a hack to exclude 15.04 PackageDeclarations, but that's not effective when we have distinct declarations for post-15.04.

I recall we agreed on having globally unique snap-ids, except for 15.04, so in this context both rolling-core and 16 package declaration should reuse the same snap-bucket. It needs data migration in production.