Removes old key location via preinst in securedrop-keyring packages
Removes old key location via preinst in securedrop-keyring packages

The Ansible playbooks have historically installed the SecureDrop signing
key to /etc/apt/trusted.gpg. Since the securedrop-keyring package
installs the keyring to /etc/apt/trusted.gpg.d/securedrop-keyring.gpg
instead, we need to clean up keys installed in the old location, to
ensure that apt finds only one relevant key to authenticate SecureDrop
packages. This gives us a single point of update to bump key expiry, or
even rotate keys, on the SecureDrop servers.

conorsch/securedrop,heartsucker/securedrop,micahflee/securedrop,ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,micahflee/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,garrettr/securedrop,ageis/securedrop,conorsch/securedrop,garrettr/securedrop,ageis/securedrop,conorsch/securedrop,micahflee/securedrop,ageis/securedrop,heartsucker/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,garrettr/securedrop,conorsch/securedrop,ehartsuyker/securedrop,ageis/securedrop,micahflee/securedrop,ehartsuyker/securedrop,garrettr/securedrop