Write tests that ensure hook_update_N is properly run

Problem/Motivation

This is step 2 for #2447573: [meta] Make sure 8.x - 8.x hook_update_N() testing is possible → .

Proposed resolution

The script/db generated from #2497323: Create a php script that can dump a database for testing update hooks → will be loaded by the tests, update hooks will be run, and changes can then be asserted by the tests.

Remaining tasks

• Write a few tests that alter tables that are part of the db dump (node, users, etc).
• Figure what else, if anything, needs to be tested in this patch

User interface changes

API changes