Remove Block class dependency from Gin Social Auth login block configuration

Problem/Motivation

#3586185: Remove Block Class module from Varbase Content Base recipe

The Gin Social Auth login block configuration includes a dependency on the
block_class module and related third-party settings. Since the
block_class module is no longer included in Varbase, this creates
unnecessary configuration dependencies and may cause config import warnings or
failures when the module is not installed.

Removing the dependency ensures the block configuration remains compatible with the updated Varbase setup and avoids unused third-party configuration.

Proposed resolution

• Remove block_class from module dependencies.
• Remove third_party_settings.block_class configuration.
• Keep Gin Social Auth login block configuration clean and module-agnostic.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ✅ Automated unit/functional testing coverage
• ✅ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes
• ❌ Release varbase-11.0.0-alpha1, varbase_starter-1.0.0-alpha1, varbase_auth_base-1.0.0-alpha1

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• chore: #3586281 Remove Block class dependency from Gin Social Auth login block configuration