Make implicit audits by the Owners tool use modern code

Summary:
Ref T10978. This updates audits triggered by Owners to use a modern transaction. Minor changes:

• After D17264, we no longer need the "AUDIT_NOT_REQUIRED" fake-audits to record package membership. This no longer creates them.
• This previously saved English-language, untranslatable text strings about audit details onto the audit relationship. I've removed them, per discussion in D17263.

The "Audit Reasons" here are potentially a little more useful than the Herald/Explicit-By-Owner ones were, since the rules are a little more complex, but I'd still like to see evidence that we need them.

In particular, the transaction record now says "Owners added auditors: ...", just like Differential, so the source of the auditors should be clear:

T11118 (roughly "add several Owners audit modes", despite the title at time of writing) might impact this too. Basically, this is simple and maybe good enough; if it's not quite good enough we can refine it.

Test Plan: Ran bin/repository reparse --owners <commit> saw appropriate owners audits trigger.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10978

Differential Revision: https://secure.phabricator.com/D17266