double authentication for password protected links

[jvillafanez]

Describe the bug

When trying to access to a password protected link, the server authenticates twice

Steps to reproduce

1. Create a password protected link
2. Try to access to the link from another browser (or incognito) and use any password

Expected behavior

Request is authenticated only once

Actual behavior

There are 2 authentication calls for the request

Setup

Please describe how you started the server and provide a list of relevant environment variables or configuration files.

OCIS_XXX=somevalue
OCIS_YYY=somevalue
PROXY_XXX=somevalue

Additional context

I assume the first authentication comes from the "public_share_auth" middleware in the proxy service, and the second one from the ocdav reva service handling the request (and the authentication) in "internal/http/services/owncloud/ocdav/dav.go" in line 301