Who recalls the following?BEEEEEP. SCREEEECH. BEEBONG-BEEBONG. That’s the sound of AOL dial-up internet — a sound etched into the memory of the 1990s. For most Americans, it’s a punchline from another era. But AOL’s decision to shut down its dial-up service on September 30 is more than a quirky tech obituary. It’s another reminder of…