PageUpdaterTest and DerivedPageDataUpdaterTest fail when run in isolation.
The failure was obscured by the fact that they work if run after other tests that used schema overrides, like PreMcrRevisionStoreDBTest.

Analysis:
In response to T202116, Ib3e80eb introduced LoadBalancer::setTempTableOnlyMode() to suppresses the CONN_TRX_AUTOCOMMIT flag for a given domain. This is intended to ensure that integration tests don't use an additional database connection that is lacking the "fake" temporary tables with the "unittest_". Table prefix.

However, for this to work, the database domain passed to setTempTableOnlyMode has to include this table prefix. $lb->getLocalDomain() however does not, since MediaWikiIntegrationTestCase::setupDatabaseWithTestPrefix() sets the prefix on the connection, not the LB.

Solution:
Get the domain for setTempTableOnlyMode() from $db->getDomainID(), so it includes the freshly set table prefix.