6 files declare their use of SchedulerManager in Scheduler 2.x

ConditionDeriver.php in scheduler_rules_integration/src/Plugin/Condition/ConditionDeriver.php

EventDeriver.php in scheduler_rules_integration/src/Event/EventDeriver.php

LightweightCronController.php in src/Controller/LightweightCronController.php

SchedulerCommands.php in src/Commands/SchedulerCommands.php

SchedulerCronForm.php in src/Form/SchedulerCronForm.php

SchedulerRulesActionDeriver.php in scheduler_rules_integration/src/Plugin/RulesAction/SchedulerRulesActionDeriver.php