Fixed card link when using MkDocs development server

[mnocon]

Target: 5.0, 6.0 + same in userdoc

Stopped always forcing the "https" scheme when generating the card links.

This changes nothing for production (where https is used), but always using https didn't work with MkDocs development server (mkdocs serve) which uses HTTP.

Example: https://ez-systems-developer-documentation--3325.com.readthedocs.build/en/3325/discounts/discounts/

[github-actions]

Preview of modified files: no change to preview.

[github-actions]

Summary

Status	Count
🔍 Total	736679
🔗 Unique	14794
✅ Successful	6208
⏳ Timeouts	0
🔀 Redirected	0
👻 Excluded	730463
❓ Unknown	0
🚫 Errors	8
⛔ Unsupported	0

Errors per input

Errors in site/release_notes/ibexa_dxp_v4.3/index.html

• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-5.0/site/personalization/configure_models/index.html#trigger-model-build (at 14460:10) | Cannot find fragment

Errors in site/release_notes/ibexa_dxp_v4.6/index.html

• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/filters/index.html#commerce-specific-filters (at 18611:39) | Cannot find fragment
• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/recommendation_models/index.html#submodels (at 18607:175) | Cannot find fragment

Errors in site/resources/new_in_doc/index.html

• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/content_management/block_reference/index.html#bestsellers-block (at 19447:14) | Cannot find fragment
• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/recommendation_models/index.html#dynamic-attributes (at 18848:33) | Cannot find fragment
• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/recommendation_models/index.html#submodels (at 19318:14) | Cannot find fragment
• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/recommendation_models/index.html#time-slot-based-models (at 18855:33) | Cannot find fragment
• [ERROR] file:///home/runner/work/documentation-developer/documentation-developer/repositories/userdoc-4.6/site/personalization/triggers/index.html#trigger-types (at 19169:14) | Cannot find fragment

Full Github Actions output