Nick Reiner celebrated his birthday on the red carpet alongside his dad, Rob Reiner, 11 years ago. This year, he’ll spend it behind bars, accused of murdering the famed filmmaker and his mom, Michele Reiner. Nick, who turns 33 on Monday, is currently being held without bail at Los Angeles’ Twin Towers Correctional Facility, where his first birthday in custody will be treated just like any ordinary day. “Birthdays are treated like every other day, no special treatment from LASD,” a Los Angeles County Sheriff’s Department representative exclusively told Page Six in response to a public records request. That means Nick won’t be getting any…