Revert "Issue #3414993 by alexpott: Add ConfigImporter to \Drupal\Core\Config\Importer\MissingContentEvent"

This reverts commit eafa8564.

Issue #3232097 by daffie, longwave: [Symfony 6] Add "array" type hint to methods overriding Symfony\Component\EventDispatcher\EventSubscriberInterface::getSubscribedEvents()

Issue #3055198 by catch, longwave, mikelutz, alexpott: [Symfony 5] Symfony/Component/EventDispatcher/Event is deprecated in Symfony 4.3 use Symfony/Contracts/EventDispatcher/Event instead

Issue #2788777 by alexpott, bircher, jribeiro, Eli-T, mpotter, douggreen, GoZ, DamienMcKenna, Dane Powell, jibran, szeidler, Alumei, andypost, dawehner, johndevman: Allow a site-specific profile to be installed from existing config

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2361423 by alexpott, larowlan, dixon_, swentel: Add a step to config import to allow contrib to create content based on config dependencies