Issue #3026434 by tedbow, tim.plunkett, xjm, phenaproxima, plach, Kristen Pol, alexpott: Ensure that Layout Builder Inline Blocks doesn't assume section storage internals

(cherry picked from commit 09a6d81ec9dd5822d4798f2343704fb72f4c865d)
(cherry picked from commit 6a6516ab)