Backport of auth/ldap: fix login errors into release/1.16.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #26200 to be assessed for backporting due to the inclusion of the label backport/1.16.x.

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@fairclothjm
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The below text is copied from the body of the original PR.

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This fixes 2 ldap auth login errors

• Missing entity alias attribute value

  • Vault relies on case insensitive user attribute keys for mapping user attributes to entity alias metadata. This sets the appropriate configs in the cap library.

• ldap group search anonymous bind regression

  • Anonymous group searches can be rejected by some LDAP servers if they contain a userDN. This sets the configs in the cap library to specify unauthenticated binds for anonymous group searches should exclude a DN.

Closes #26171
Closes #26183

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Overview of commits

• 7d575bf

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CI Results:
All Go tests succeeded! ✅

[fairclothjm]

closing in favor of #26206