Overridden view block title should be set on the view itself

Ran test-only feature

1) Drupal\Tests\block\Functional\Views\DisplayBlockTest::testBlockRendering
Failed asserting that the text of the element identified by '#test-view-block--title' equals 'Custom title'.
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'Custom title'
+'test_view_block'
/builds/issue/drupal-3461896/core/tests/Drupal/Tests/WebAssert.php:807
/builds/issue/drupal-3461896/core/modules/block/tests/src/Functional/Views/DisplayBlockTest.php:277
FAILURES!
Tests: 6, Assertions: 101, Failures: 1.

Code wise believe this makes sense $this->configuration['views_label'] doesn't appear to be in $output['#title'] = ['#markup' => $this->view->getTitle(), '#allowed_tags' => Xss::getHtmlTagList()];

So checking views_label probably didn't make sense. Think breaking up was the right call.

Only think I'm iffy about is the removal of getConfiguration() if that's going to require any BC dance.

otherwise LGTM.

small tweak on the test

Since this is a test-only nit, moving back to RTBC.

Left a question in the MR.