Issue #1798386 by Lars Toomre: Remove t() from test assert messages in user module

core/modules/user/lib/Drupal/user/Tests/UserAdminTest.php

.../user/lib/Drupal/user/Tests/UserAuthmapAssignmentTest.php

...dules/user/lib/Drupal/user/Tests/UserAutocompleteTest.php

core/modules/user/lib/Drupal/user/Tests/UserBlocksTests.php

core/modules/user/lib/Drupal/user/Tests/UserCancelTest.php

core/modules/user/lib/Drupal/user/Tests/UserEditTest.php

...es/user/lib/Drupal/user/Tests/UserEntityCallbacksTest.php

...s/user/lib/Drupal/user/Tests/UserLanguageCreationTest.php

core/modules/user/lib/Drupal/user/Tests/UserLanguageTest.php

core/modules/user/lib/Drupal/user/Tests/UserLoginTest.php

...odules/user/lib/Drupal/user/Tests/UserPermissionsTest.php

core/modules/user/lib/Drupal/user/Tests/UserPictureTest.php

...dules/user/lib/Drupal/user/Tests/UserRegistrationTest.php

.../modules/user/lib/Drupal/user/Tests/UserRoleAdminTest.php

...es/user/lib/Drupal/user/Tests/UserRolesAssignmentTest.php

core/modules/user/lib/Drupal/user/Tests/UserSaveTest.php

core/modules/user/lib/Drupal/user/Tests/UserTimeZoneTest.php

...dules/user/lib/Drupal/user/Tests/UserTokenReplaceTest.php