It did live in the container as indicated by the output of ls in my original post. I did finally figure out what the problem was, however.
When I changed the packages the system installed, I only added the mariadb libraries during the setup.sh install step. That step runs under the build container setup of the dockerfile. The production container also uses the same file with the run option: setup.sh run. Once I added the mariadb library under that step, the container created the database without a hitch.
From what I understand, this was a library issue. I’m not familiar with dynamic/static libraries, so my best guess is that the error message was misleading.