[omniauth-ldap]️ Replace gitlab_omniauth-ldap with original

What does this MR do and why?

[omniauth-ldap]️ Replace gitlab_omniauth-ldap with original

Original omniauth-ldap gem is now actively maintained by me (@pboling)

• includes all changes from the gitlab fork
• Adds RBS types
• Support for SCRIPT_NAME (i.e. protecting a subdirectory / sub-path)
• Support for LDAP Password Policy Draft Proposal v11
• Support for JSON bodies
• Support for custom LDAP attributes mapping
• Support for LDAP-based SSO identity via HTTP Header (off by default)
• Complete documentation
• Well-tested support for Ruby v2+, rack v1+, omniauth v1.2+

Changelog: added

NOTE: the documentation for the Changelog trailer is contradictory.

It says:

add the string Changelog: feature

see changelogs.md

and then below lists all supported trailers and feature isn't on the list, but has added in place of feature (see: changelogs.md)

References

Request for this MR was made by @dblessing here: gitlab-foss#13280 (comment 2869978044)

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.