Bug 29754: (QA follow-up) Minor tests tweaks

Bug 29754: (QA follow-up) Minor tests tweaks

This patch does two things:

- Wraps the new SIP tests in a single transaction. We do that to avoid
  sub-test interference, specially when test files get big. The provided
  tests are correct and don't require previous tests data.
- Migrated from the introduced 'diag' calls to 'note', as I just learned
  they are the same, but 'note' is only displayed when in verbose mode.
  Which is great to avoid unnecessary noise in Jenkins.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>