Backport of fix a bug reading auth mount using sys/internal/ui/mount endpoint when filter paths are enforced into release/1.15.x

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

Backport

This PR is auto-generated from #23802 to be assessed for backporting due to the inclusion of the label backport/1.15.x.

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

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Addresses https://hashicorp.atlassian.net/browse/VAULT-21207

Reading an "auth" mount using "sys/internal/ui/mounts/" when filter paths are enforced returns 500 error code from the secondary:

failed to read a mount point in allow mode, Error making API request.
        
        URL: GET https://127.0.0.1:49227/v1/sys/internal/ui/mounts/auth/d0681fa6-a5be-4d7e-8c38-c443325bb3ee
        Code: 500. Errors:
        
        * unable to retrieve route entry for mount path

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Overview of commits

• 26bae55

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