Issue #1929420 by quietone, krlucas, kay_v, seiplax, floydm, alexpott, mlncn,...

Issue #1929420 by quietone, krlucas, kay_v, seiplax, floydm, alexpott, mlncn, nlisgo, gulab.bisht, scor, larowlan, longwave, pameeela: [backport] $account->getDisplayName() should be used when outputing username in RDF module