Issue #3432256 by saurabh rawat, thhomas, longwave: Remove deprecated code from include files

core/includes/bootstrap.inc

core/includes/common.inc

core/includes/install.inc

core/includes/module.inc

core/includes/theme.inc

...b/Drupal/Core/Form/EventSubscriber/FormAjaxSubscriber.php

core/modules/file/file.field.inc

core/modules/migrate/src/MigrateExecutable.php

core/tests/Drupal/KernelTests/Core/Asset/LegacyAssetTest.php

...Drupal/KernelTests/Core/Bootstrap/LegacyBootstrapTest.php

...tests/Drupal/KernelTests/Core/Common/LegacyCommonTest.php

...ts/Drupal/KernelTests/Core/Extension/ModuleLegacyTest.php

...rupal/KernelTests/Core/Site/LegacySettingsRewriteTest.php

core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php

...l/KernelTests/Core/Theme/ThemeRenderAndAutoescapeTest.php