Update recently added logging to be less verbose

In 20d9642c and parent commits, log levels were
recategorized to be less verbose when using the
level INFO and lower. These levels should not
print any information redundant to the end user.

This commit fixes recently added uses of logging
that are not consistent with the abovementioned
categorization, in particular:

- logs in ssh_strict_fopen should not have
  the RARE/WARNING level since failing to open
  a file may not be an issue at all (e.g., when
  trying to open the knownhosts file).

- logging the username used in authentication
  or proxyjump-related information should be done
  at the DEBUG level, otherwise it could pollute
  the output of, e.g., curl.

Signed-off-by: Pavol Žáčik <pzacik@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

src/socket.c

@@ -1435,7 +1435,7 @@ ssh_socket_connect_proxyjump(ssh_socket s)
 
     session = s->session;
 
-    SSH_LOG(SSH_LOG_INFO,
+    SSH_LOG(SSH_LOG_DEBUG,
             "Connecting to host %s port %d user %s through ProxyJump",
             session->opts.host,
             session->opts.port,
@@ -1515,7 +1515,7 @@ ssh_socket_connect_proxyjump(ssh_socket s)
     /* transferred to the jump_thread_data */
     jump_session = NULL;
 
-    SSH_LOG(SSH_LOG_INFO,
+    SSH_LOG(SSH_LOG_DEBUG,
             "Starting proxy thread to host %s port %d user %s, callbacks=%p",
             jump_thread_data->next_jump->hostname,
             jump_thread_data->next_jump->port,