By Eric Bradner, CNN (CNN) — Spencer Pratt might be a candidate uniquely suited for the moment: An elder millennial with everywhere-all-the-time social media instincts, bluntly spelling out Los Angeles’ challenges with homelessness, crime and mismanagement and laying blame at the feet of its entrenched Democratic establishment. The 42-year-old former reality television star’s willingness to be raw and provocative, on the bet that authenticity is…