Patch for net-ldap downgrade to resolve multi ldap host support

What does this MR do and why?

Describe in detail what merge request is being backported and why The net-ldap gem was updated from version 0.17.1 to 0.18.0 in Gitlab version 16.1 to take advantage of a recent SNI support capability added to the library itself. A bug was later identified within the updated version of library Multiple servers in hosts LDAP configuration fails (#416226 - closed) where multiple LDAP hosts support is broken.

We are working with the maintainer of net-ldap to release a newer version with the fix included however that may take some time, and in the interim it's important to restore the multi host support for our users, by downgrading the lib version back. This was already done on 16.2 via Downgrade net-ldap (!125855 - merged)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).
• This MR has been approved by a maintainer (only one approval is required).
• Ensure the e2e:package-and-test-ee job has either succeeded or been approved by a Software Engineer in Test.

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