Benjamin Schneider, who refers to himself as Reckless Ben on social media, recently walked a slackline strung between two skyscraper towers 40 stories above Figueroa Street in downtown L.A. Add criminal tightrope walking to the list of problems besieging Oceanwide Plaza, the unfinished, bankrupt, vandalized, graffitied towers marring the skyline of downtown Los Angeles. Schneider told The Times on Saturday …