ci/config: remove RELEASES_SERVER

This does not seem to be used anywhere here and can be misleading

Signed-off-by: Mathieu Tortuyaux <[email protected]>

Author: tormath1

ci-automation/ci-config.env

@@ -12,7 +12,6 @@ BUILDCACHE_SERVER="${BUILDCACHE_SERVER:-bincache.flatcar-linux.net}"
 BUILDCACHE_PATH_PREFIX="/srv/bincache"
 BUILDCACHE_USER="bincache"
 
-RELEASES_SERVER="mirror.release.flatcar-linux.net"
 CONTAINER_REGISTRY="ghcr.io/flatcar"
 RELEASES_JSON_FEED="https://www.flatcar.org/releases-json/releases.json"