DX: reorganize test components: `canvas_test_sdc` should have its (intentionally invalid) SDCs moved to `canvas_test_sdc_invalid`

Overview

Changes like https://git.drupalcode.org/project/canvas/-/merge_requests/663#note_710706 on #3576578: Inform SDC/code component developers of nonsensical `type: array` prop restrictions: `maxItems <2` and https://git.drupalcode.org/project/canvas/-/merge_requests/706/diffs#6a8... on #3572553: Save Multi-Value Prop Configuration for Code Components are distracting/frustrating. They should not be necessary.

Proposed resolution

1. Split canvas_test_sdc_invalid off from canvas_test_sdc, make it contain all test SDCs that are invalid. Update https://git.drupalcode.org/project/canvas/-/merge_requests/663#note_710706 and \Drupal\Tests\canvas\Kernel\Plugin\Canvas\ComponentSource\SingleDirectoryComponentTest::testDiscovery() accordingly. That means:
   • $this->findIneligibleComponents(SingleDirectoryComponent::SOURCE_PLUGIN_ID, 'canvas_test_sdc') should match the empty array.
   • Every SDC that is currently being found as ineligible must be moved to the canvas_test_sdc_invalid module.
2. Similarly update \Drupal\Tests\canvas\Kernel\Plugin\Canvas\ComponentSource\SingleDirectoryComponentTest::testRenderComponentLive to no longer test the rendering of
   

   User interface changes

   None.