Issue #2443381 by pjbaert: Make all test functions public

core/modules/block/src/Tests/Views/DisplayBlockTest.php

core/modules/dblog/src/Tests/DbLogTest.php

core/modules/search/src/Tests/SearchBlockTest.php

...s/simpletest/src/Tests/MissingCheckedRequirementsTest.php

core/modules/system/src/Tests/Pager/PagerTest.php

core/modules/system/src/Tests/Session/SessionHttpsTest.php

core/modules/user/src/Tests/UserCreateFailMailTest.php

core/modules/user/src/Tests/UserCreateTest.php

core/modules/views/src/Tests/Handler/FilterDateTest.php

.../modules/views/src/Tests/Plugin/DisplayAttachmentTest.php

core/modules/views/src/Tests/Wizard/BasicTest.php

core/modules/views_ui/src/Tests/PreviewTest.php