This flag is on by default, and serves to enable (or disable) the
public TLS by default feature.
It differs from the PublicSSLCertificateAutogenerated flag in the fact
that it works with mistral, while PublicSSLCertificateAutogenerated
works with certmonger in the overcloud.
Change-Id: If553ecff26d5ecd529c37ca438e0ba1795e9ecca