In the Herald test console, don't consider transactions that Herald rules applied

Summary:
Depends on D20546. Ref T13283. Currently, if you do something (transactions "A", "B") and Herald does some things in response (transaction "C"), Herald acts only on the things you did ("A", "B") since the thing it did ("C") didn't exist yet, until it ran.

However, if you use the test console to test rules against the object we'll pick up all three transactions since they're all part of the same group. This isn't ideal.

To fix this, skip transactions which Herald applied, since it obviously didn't consider them when it was evaluating.

Test Plan:

• Created a revision, in the presence of a Herald rule that adds reviewers.
• Then, ran the revision through the test console.
• Before: saw the "Herald added reviewers: ..." transaction in the transaction group Herald evaluated.
• After: saw only authentic human transactions.

{F6464064}

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13283

Differential Revision: https://secure.phabricator.com/D20547