<?php
$string = <<< 'STR'
foo bar __level [
$save = 123,
Info = '1234'
]
{Lorem ipsum dolor sit 
amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut 
labore et dolore magna aliqua. 
Ut enim ad minim veniam, quis nostrud exercitation ullamco 
laboris nisi ut aliquip 
ex ea commodo consequat. Duis aute irure dolor in 
reprehenderit in voluptate 
velit esse cillum dolore eu fugiat nulla pariatur.}
STR;
 
 
$string = preg_replace("/(?=\R)\R+(?=.*\R{)/s", '', $string);
var_dump($string);

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