Remove reference to load plugin, LoadEntity

@baliram.patil, thanks!

Without the patch a grep finds two instances of LoadEntity

$ grep -r LoadEntity core
core/tests/Drupal/KernelTests/Core/Entity/EntityLoadByUuidTest.php:  public function testLoadEntityByUuidAccessChecking() {
core/modules/migrate/src/Plugin/MigrationInterface.php:   * @see Drupal\migrate_drupal\Plugin\migrate\load\LoadEntity::processLinkField()

and with the patch only one

$ grep -r LoadEntity core
core/tests/Drupal/KernelTests/Core/Entity/EntityLoadByUuidTest.php:  public function testLoadEntityByUuidAccessChecking() {

And tests are still passing.