In MDL-71257 there was some name changing from slave->replica and master->primary in the core_dml area of Moodle.

Due to those changes, the following will undergo final deprecation in Moodle 6.0:

• lib/dml/moodle_read_slave_trait.php
• moodle_database::want_read_slave
• moodle_database::perf_get_reads_slave