Drain the peer update channels after the bootstrap in the realstack
test so its fan-out assertions can only be satisfied by the operation
under test; use assert with a length guard for diffMappings conditions
under test; drop the duplicate labelgen package comment and two stale
provider-bootstrap comments in the e2e suite; add context to the
exclusion test's account-ID assertion.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>