Remove error logging of missing boto libraries
Remove error logging of missing boto libraries

Current behavior always error logs, even if the module is not going to
be used. The loader will raise a proper error if it's attempted
accessed without having loaded properly anyway, and if that happens I'm
assuming you'll turn on debug logging and look for the cause. The
loader also logs which modules are not loaded and their reason, thus
there's no point in repeating the module name in the error message.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt