Issue #2707261 by alexpott, jhodgdon: Calling moduleInvokeAll in Help block is wrong

core/modules/help/src/Plugin/Block/HelpBlock.php

core/modules/help/src/Tests/HelpBlockTest.php

...s/help/tests/modules/help_page_test/help_page_test.module

...p/tests/modules/help_page_test/help_page_test.routing.yml

...sts/modules/help_page_test/src/HelpPageTestController.php

.../modules/more_help_page_test/more_help_page_test.info.yml

...ts/modules/more_help_page_test/more_help_page_test.module