BUGFIX: Fix usage of node.nodeAggregateId in fluid

[ahaeslich]

Fix usage in Index fluid template of Neos\Neos\Controller\Service\NodesController

Relates: #4156

Review instructions

• Try to set a link to a node in a text block OR
• Try to search for a node in the reference or references editor

Checklist

• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions