Handle Rails SSL configuration for a custom load balancer

What does this MR do?

Update Rails SSL configuration to handle case a custom Load Balancer is used outside of Ansible inventory.

• gitlab_single_node_without_lb - should be set to true manually for standalone Rails environment without load balancer. This is needed to preserve previous behaviour for inventories where LB was configured outside of GET - !1345 (comment 1952306805)
• Updating 1k - GCP example to 1k without LB for better example coverage

Related issues

Related to Ansible Rails Config - nginx listener port 80 n... (#893 - closed)

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up-to-date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
  • MR has no new security alerts in the widget from the Secret Detection and IaC Scan (SAST) jobs.
• Code:
  • Check the area changed works as expected. Consider testing it in different environment sizes (1k,3k,10k,etc.).
  • Documentation created/updated in the same MR.
  • If this MR adds an optional configuration - check that all permutations continue to work.