Revert "Revert "Revert "Temporarily disable CSP in Nextcloud."""

This reverts commit 2f132439.

This actually solved the issue (Collabora Online worked!) but this is
not a long-term solution, just a test.

conf.d/nextcloud.shore.co.il.conf

@@ -27,8 +27,5 @@ server {
         include                 snippets/proxy-headers.conf;
         proxy_hide_header       X-Frame-Options;
         client_max_body_size    512m;
-        # Temporary measure to test a Collabora Online issue, should not be left
-        # as is.
-        proxy_hide_header       content-security-policy;
     }
 }