Fix snap refresh verification job dependency (bugfix) (#1519)

Fix snap refresh verification job dependency

When implementing changes for the gadget/snapd/kernel snap refresh[1],
one of the job dependencies was not updated properly.

The `snapd/reboot-after-snap-refresh-{type}-{name}-to-stable-rev` job
does not exist anymore, so the
`snapd/snap-verify-after-refresh-{type}-{name}-to-stable-rev` should
depend on the refresh job itself (which was modified in the
aforementioned PR to do the reboot itself)

[1]: #1124

providers/base/units/snapd/jobs.pxu

@@ -63,7 +63,7 @@ plugin: shell
 estimated_duration: 30s
 category_id: snapd
 user: root
-depends: snapd/reboot-after-snap-refresh-{type}-{name}-to-stable-rev
+depends: snapd/snap-refresh-{type}-{name}-to-stable-rev
 command:
  path="$PLAINBOX_SESSION_SHARE/{name}_snap_revision_info"
  snap_update_test.py --verify-refresh --info-path "$path" {name}