CHICAGO — Former Alderman Daniel Solis, whose unprecedented turn as an FBI mole helped the feds take down two princes of Chicago’s Democratic political machine, is expected to be called as a defense witness next week in the corruption trial of his former colleague, ex-Alderman Ed Burke. The undercover recordings made by Solis have been the centerpiece of Burke’s ongoing trial, but Solis himself has been something of an enigma. Prosecutors opted not to call Solis as their own witness, and while Burke’s lawyers promised the judge they’d call him, it was not mentioned to the jury in opening state…
