Leave the /styles/bootstrap.less file as it is. That gets loaded separately.
This line in the error log has me curious:
[28-Jun-2017 17:04:39 America/Chicago] PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 64 bytes) in /home/ipao/public_html/revista/lib/pkp/lib/vendor/oyejorge/less.php/lib/Less/Visitor.php on line 45
It may be that you’re just running out of memory when trying to compile the stylesheet. If that’s the case, you’ll need to free up more memory on your server.