Handle migration tests for removing RDF

@quietone, after applying the (real) patch in #9 I'm still seeing a number of references to rdf in Drupal\Tests\migrate_drupal\Unit\MigrationStateUnitTest. I can't claim I fully understand what that test does, but I suspect we need to do something with those references to rdf. Now I see that's a remaining task!

Also, in the (new) Drupal\Tests\rdf\Functional\Migrate::Upgrade7Test I *think* this needs rdf added to the $modules array since rdf will no longer get enabled automatically once it is removed from the standard profile. Or maybe that happens when it is actually removed from the standard profile?

That's all that jumped out at me. Looking good! I guess I'll throw this back to NW.

Thanks, @quietone!

My concerns in #10 are completely addressed. But regarding getMissingPaths thing that I brought up in the migrate meeting: We intend to leave RDF in getMissingPaths in the D7 migrate_drupal_ui ReviewPage tests, right?

+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MultilingualReviewPageTest.php
@@ -41,6 +41,9 @@ class MultilingualReviewPageTest extends MultilingualReviewPageTestBase {
@@ -113,7 +116,6 @@ protected function getAvailablePaths() {

@@ -113,7 +116,6 @@ protected function getAvailablePaths() {
       'Phone',
       'Poll',
       'Profile',
-      'RDF',
       'Search',
       'Search embedded form',
       'Shortcut',
@@ -167,6 +169,8 @@ protected function getMissingPaths() {

@@ -167,6 +169,8 @@ protected function getMissingPaths() {
       'Options',
       'Path translation',
       'Picture',
+      // @todo Remove RDF in https://www.drupal.org/node/3267515
+      'RDF',
       'References',
       'References UUID',
       'Translation redirect',

If I haven't somehow misunderstood, I think we need to remove the @todos in the getMissingPath methods.

Corrected patch as per #14.

This patch is correct per my understanding of the "getMissingPaths" plan. I'm going to RTBC it.

This looks fine to me - various @todos but all because it's a pre-requisite to the removal issue.

Committed/pushed to 10.0.x and cherry-picked to 9.4.x thanks!