About halfway through David F. Sandberg’s “Shazam! Fury of the Gods,” our hero’s hometown of Philadelphia gets sealed into a giant, magical bubble. What better metaphor for this series’ place in the DC Universe, a sprawling franchise that never quite cohered and is now getting a major retooling at the hands of new brass, do you need? When Sandberg’s first “Shazam!” film arrived in theaters in March 2019, it was on the heels of massive box office successes like “Aquaman,” “Justice League,” and “Wonder Woman” — the salad days of what was then known as the DC Extended Universe — and a seemingly clever time to release the closest the DCEU had gotten to a standalone film for the younger set (the first “Suicide Squad,” of course being for a more mature audience).