I had this exact same problem on my first '92 Malibu (not that it was related to the color...I just like to brag). Kept draining the battery when sitting out in the sun and would set the alarm off (which really pissed off the manager who sat next to the office carpark

). I only found it when I noticed that the high beam indicator light was on, but the headlights were down, while driving home after a hot day. I found that I could duplicate the issue if I pull back on the headlight stalk ever so slightly.
I think, from memory, that I overcame it by pushing the stalk forward (into to high beam mode) whenever the she was parked. Not a permanent fix, but it worked for me.
Another symptom was that I had previously installed a resistor to allow me to have the 'flash to pass' option, whenever I used the indicators the headlights would pop up. I uninstalled the resistor to fix that.
Motor Neurone Disease chose me, I choose Voluntary Assisted Dying.