Bump default TLS timeout for leafnode connections
Add checks for when cert_file or key_file are missing in TLS config
Signed-off-by: Waldemar Quevedo <wally@synadia.com>
If server solicits leaf node TLS connection and needs to verify
the server certificate, it did not have the root CAs set in its
config.
Signed-off-by: Ivan Kozlovic <ivan@synadia.com>