R1:0b93685cc999

Fix undefined variable in HeraldAction

Summary: `$no_permission` is only defined within `if ($object instanceof PhabricatorPolicyInterface)`, thus move the check for `if ($no_permission)` into that clause.

Test Plan: Read the code.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25741